Transport Path Correction Techniques and Related Systems, Methods and Devices

ABSTRACT

A printer deposits material onto a substrate as part of a manufacturing process for an electronic product. At least one mechanical component experiences mechanical error, which is mitigated using transducers that equalize position of a transported thing, e.g., to provide an “ideal” conveyance path; a substrate conveyance system and/or a printhead conveyance system can each use transducers in this manner to improve precise droplet placement. In one embodiment, errors are measured in advance, with corrections being “played back” during production runs to mitigate repeatable transport path error. In a still more detailed embodiment, the transducers can be predicated on voice coils, which cooperate with a floatation table and floating, mechanical pivot assembly to provide frictionless, but mechanically-supported error correction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. patent applicationSer. No. 15/816,443 filed on Nov. 17, 2017, which is a continuation ofco-pending U.S. patent application Ser. No. 15/642,037 filed on Jul. 5,2017, and issued as U.S. Pat. No. 9,961,782, which claims benefit ofU.S. Provisional Application Ser. No. 62/489,768 filed on Apr. 25, 2017,U.S. Provisional Application Ser. No. 62/359,969 filed on Jul. 8, 2016,and U.S. Provisional Patent Application Ser. No. 62/459,402 filed onFeb. 15, 2017. Each of the aforementioned applications is incorporatedby reference.

U.S. Utility Patent Application Ser. No. 15/816,443 also incorporates byreference the following documents: U.S. Pat. No. 9,352,561 (U.S. Ser.No. 14/340,403), filed as an application on Jul. 24, 2014 on behalf offirst inventor Nahid Harjee for “Techniques for Print Ink DropletMeasurement And Control To Deposit Fluids Within Precise Tolerances:” USPatent Publication No. 20150360462 (U.S. Ser. No 14/738,785), filed asan application on Jun. 12, 2015 on behalf of first inventor Robert B.Lowrance for “Printing System Assemblies and Methods:” US PatentPublication No. 20150298153 (U.S. Ser. No. 14/788,609), filed as anapplication on Jun. 30, 2015 on behalf of first-named inventor MichaelBaker for “Techniques for Arrayed Printing of a Permanent Layer withImproved Speed and Accuracy:” and U.S. Pat. No. 8,995,022, filed as anapplication on Aug. 12, 2014 on behalf of first named inventor EliyahuVronsky for “Ink-Based Layer Fabrication Using Halftoning To ControlThickness.” Each of these aforementioned applications is herebyincorporated by reference.

BACKGROUND

Certain types of industrial printers can be applied to precisionmanufacture, for example, to the fabrication of electronic devices.

To take one non-limiting example, ink jet printers can be used todeposit one or more super-thin layers of an electronic display device ora solar panel device. The “ink” in this case differs from conventionalnotions of ink as a dye of a desired color, and instead can be anorganic monomer deposited as discrete droplets that spread somewhat andmeld together, but that are not absorbed and instead retain a deliberatelayer thickness that helps impart structural, electromagnetic or opticalproperties to the finished device; the ink is also typicallydeliberately made to be translucent with a resultant layer being used togenerate and/or transmit light. A continuous coat of the ink depositedby the printing is then processed in place (e.g., cured usingultraviolet light, or otherwise baked or dried) to form a permanentlayer having a very tightly regulated thickness, e.g., 1-10 microns,depending on application. These types of processes can be used todeposit hole injection layers (“Hlls”) of OLEO pixels, hole transferlayers (“HTLs”), hole transport layers (“HTLs”), emissive or lightemitting layers (“EMLs”), electron transport layers (“ETLs”), electroninjecting layers (“Ells”), various conductors such as an anode orcathode layer, hole blocking layers, electron blocking layers,polarizers, barrier layers, primers, encapsulation layers and othertypes of layers. The referenced materials, processes and layers areexemplary only. In one application, the ink can be deposited to create alayer in each of many individual electronic components or structures,for example, within individual microscopic fluidic reservoirs (e.g.,within “wells”) to form individual display pixels or photovoltaic celllayers; in another application, the ink can be deposited to havemacroscopic dimensions, for example, to form one or more encapsulationlayers cover many such structures (e.g., spanning a display screen areahaving millions of pixels).

The required precision can be very fine; for example, a manufacturer'sspecification for fabricating a thin layer of an organic light emittingdiode (“OLEO”) pixel might specify aggregate fluid deposition within apixel well to a resolution of a picoliter (or to even a greater level ofprecision). Even slight local variations in the volume of depositedfluid from specification can give rise to problems. For example,variation in ink volume from structure-to-structure (e.g.,pixel-to-pixel) can give rise to differences in hue or intensitydifferences or other performance discrepancies which are noticeable tothe human eye; in an encapsulation or other “macroscopic” layers, suchvariation can compromise layer function (e.g., the layer may notreliably seal sensitive electronic components relative to unwantedparticulate, oxygen or moisture), or it can otherwise give rise toobservable discrepancies. As devices become smaller and smaller, and thepertinent layers become thinner and thinner, these problems become muchmore significant. When it is considered that a typical application canfeature printers having tens-of-thousands of nozzles that depositdiscrete droplets each having a volume of 1-30 picoliters (“pl”), andthat manufacturing process corners for the printheads can lead toinoperative nozzles and individual error in any of droplet size, nozzlelocation, droplet velocity or droplet landing position, thereby givingrise to localized ink volume delivery variation, it should beappreciated that there are very great challenges in producing thin,homogeneous layers that closely track desired manufacturingspecifications.

One source of error in achieving fine precision relates to the use ofmechanical components in the fabrication processes relative to the scaleof products being manufactured. As a non-limiting example, most printershave mechanical transport systems that move one or more printheads, asubstrate, or both in order to perform printing. Some printers alsofeature transport systems for rotating or offsetting components (e.g.,moving or rotating printheads to change effective pitch betweennozzles); each of these transport systems can impart fine mechanical orpositioning error that in turn can lead to non-uniformity. For example,even though these transport systems typically rely on high-precisionparts (e.g., precision tracks or edge guides), they can still impartjitter or translational or rotational inaccuracy (e.g., such asmillimeter, micron or smaller scale excursions in the transport path)that makes it difficult to achieve the required precision and uniformitythroughout the transport path lengths used for manufacture. To providecontext, an apparatus used to fabricate large size HDTV screens mightfeature a “room sized” printer which is controlled so as to deposit anultra-thin material layer on substrates meters wide by meters long, withindividual droplet delivery planned to nanometerscale coordinates; thetransport paths in such an apparatus can be meters in length. Note thatthere are many other mechanical components that can give rise to someform of error in such a system, for example, transport path systems usedto interchange printheads, camera assemblies to align or inspect asubstrate, and other types of moving parts. In such a system, even veryfine precision mechanical parts can create excursions that affect thenanometer-scale coordinates just referenced. Thus, the required layersbecome thinner and thinner, and the require precision becomes smallerand smaller relative to the product being fabricated, it becomes evenmore imperative to carefully control and/or mitigate sources ofpotential positional error.

There exist some conventional techniques for reducing positional andtranslational error generally in these types of fabrication systems.First, a substrate can be coarsely-aligned with printer transport andthen manually fine-aligned (potentially repeatedly during thefabrication process); such a process is time-consuming, i.e., itgenerally impedes the goal of having an automated, fast, assembly linestyle process for producing consumer products. It is also generallyquite difficult to obtain the required micron- or nanometer-precisionwith such a manual process. There also are some errors that cannot beadequately addressed with such a technique, for example, errors causedby transport path discrepancies, as just introduced above (e.g., errorwhich manifests itself after a substrate has been aligned). As a secondexample, US Patent Publication No. 20150298153 relates to processes thatmeasure fine positional and/or rotational errors in substrate positionand that correct for those errors in software, for example, byreassigning which nozzles are used to print or by otherwise changing thenozzle drive waveforms which are used to fire nozzles; in other words,generally speaking, these techniques attempt to “live with” finepositional and rotational error (thereby preserving print speed) andthey then attempt to adjust which nozzles are used and when and howthose nozzles are electronically controlled, so as to remedy error(e.g., using a preplanned raster without having to readjust scan pathsdependent on error). However, despite the utility of compensating foralignment error in software, the measuring and accounting for this errorand re-computing firing assignments for thousands of nozzles in softwarecan take substantial computing resources and time.

What are needed are additional techniques for correcting for motion,rotation and position error in mechanical systems in a manufacturingapparatus. Still further, what are needed are techniques for correctingfor error in a moving component of a manufacturing system in order tosimulate an “ideal” edge or transport path. Such techniques, if appliedto precision manufacturing processes, especially printing systems of thetype described, would reduce the need for substantial computingresources and time to re-render raster control data and, overall, leadto a simpler and/or faster and/or more accurate print process. Thepresent invention addresses these needs and provides further, relatedadvantages.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a substrate 103 as it is transported through anindustrial printing system along a transport path 107; at its rightside, FIG. 1 shows the substrate at two hypothetical positions (103′ and103″) with respective rotation and translation error (L1 x, L1 y, andL161). Transport path error and associated substrate rotation andtranslation error is seen as exaggerated relative to drawing scale, toassist with explanation.

FIG. 2A is a schematic diagram showing one or more transducers thatperform fine mechanical adjustments to correct for errors referenced inconnection with FIG. 1 (i.e., in this example, as part of a “gripper”that advances the substrate); in one embodiment, repeatable mechanicalerror is measured in advance, and one or more transducers “T” are drivenas a function of transport path position to correct for repeatablesubstrate rotation and translation error relative to an ideal (e.g., a“perfectly straight” or “jitter free”) transport path.

FIG. 2B depicts a transport path 107 having mechanical imperfections,just as with FIG. 1; however, in this case, transducers “T,” such asintroduced relative to FIG. 2A, are used to perform fine tuningadjustment for the substrate position and/or orientation as the gripperadvances on the path 107. The result is that the substrate now movesaccording to “ideal” motion (e.g., a perfectly straight “ideal” edgeand/or jitter free path), as represented by a virtual straight edge 223.

FIG. 2C is similar to FIG. 2B, in that it shows use of transducers “T”to correct for transport path error. However, in this case, error alsopotentially arises from a second transport path 256, in this case,manifested as the non-ideal motion of a printhead (or camera or otherassembly) as it travels along in the general direction of arrows 254.

FIG. 2D is similar to FIG. 2C in that it depicts motion of a printheadalong an edge or track 256 but, as illustrated, a printhead assembly nowalso has its own transducer assembly(ies) to provide for fine tuningpositional and rotational corrections that mitigate error in the edge ortrack 256; the result is that the printhead now also effectively travelsa virtual “ideal” path 225 (or 269, as will be discussed below).

FIG. 2E represents an alternative embodiment where error in onetransport path (e.g., the printhead transport path) can be mitigated byan error correction mechanism in a different transport path; forexample, an error correction mechanism such as transducers “T”associated with the gripper 203 can perform fine adjustments tosubstrate position or orientation that compensate for error in adifferent transport path (e.g., such as the printhead transport path).Note that corrections can be dependent on multiple variables, e.g., theycan be made to depend on time-variant motion along or position along theother transport path; for example, the transducers “T” can be controlledas the gripper 203 moves in the “y” dimension in a manner that is alsodependent on printhead assembly position along track 256, such that thesubstrate follows virtual path 107′″ or virtual path 107″″ (i.e.,depending on both gripper position and printhead assembly position).

FIG. 3A is a flow chart associated with correcting positional and/orrotational error as a transported thing is advanced along a transportpath.

FIG. 3B is an illustrative diagram showing a mechanism for correctingfor transport path error, for example, by performing compensatingcountermotions (or other error mitigation) in up to six differentdimensions (e.g., potentially including three translational dimensions,as well as yaw, pitch and/or roll).

FIG. 4A provides a plan view of a substrate, and shows a raster orscanning process; a shaded area 407 represents a single scan path, whilea clear area 408 represents another. As indicated by a dimensionallegend in the FIG., in this example, an “x” axis corresponds to across-scan dimension while a “y” axis corresponds to an in-scandimension.

FIG. 4B provides a plan, schematic view of a fabrication machine thatincludes multiple modules, one of which (415) features a printer withina controlled atmosphere.

FIG. 4C is a block diagram that illustrates one method 431 of measuring,recording and then correcting for repeatable transport path error in anindustrial printing system.

FIG. 4D illustrates a method where one or more printheads are alignedwith the gripper during an initialization process, to thereby establisha coordinate reference system used by a printer (e.g., a coordinatesystem used for a printer support table); during production, as each newsubstrate in a series is introduced into the printer, that substrate isthen also aligned to this same reference system as part of printing.Aligning each of the printhead(s) and each substrate to a commonreference system permits the printhead(s) and the substrate to beproperly aligned to each other at all times during printing.

FIG. 5 is an illustrative view showing a series of optional tiers,products or services that can each independently embody techniquesintroduced herein; for example, these techniques can be embodied in theform of software (per numeral 503), or as printer control data (pernumeral 507), to be used to control a printer to print on a substrate orotherwise to correct for repeatable error, or as a product made inreliance on these techniques (e.g., as exemplified by numeral 511, 513,515 or 517).

FIG. 6A is a detail, perspective view of one embodiment of an industrialprinter, such as the printer inside the printing module of FIG. 4B.

FIG. 6B is a detailed perspective view of an embodiment of a gripper.

FIG. 6C is a close-up, perspective view of a transducer assembly fromthe gripper of FIG. 6B.

FIG. 6D is a close-up, perspective view of a floating, mechanical pivotassembly from the gripper of FIG. 6B.

FIG. 6E is a schematic side view of the error correction systemrepresented by FIGS. 6B-6D, with an emphasis on design of the floating,mechanical pivot assembly.

FIG. 7A is a perspective view of a substrate and transport system (e.g.,for a gripper) used to measure error; a laser interferometry systemdirects light through optics 707 mounted to the gripper's displaceableor “second component” 705 or the thing being transported (e.g.,substrate 705) with interferometric techniques being used to measurevery slight (e.g., micron/milliradian scale or smaller) positional orangular deviations (including vibration).

FIG. 7B provides a side view of a printhead (or camera) travelerassembly, i.e., a camera or printhead assembly 745 moves back and forthalong traveler 747 with optics 743 mounted to the camera or printheadassembly to measure very slight positional or angular deviationsaffecting movement and orientation of assembly 745.

The subject matter defined by the enumerated claims may be betterunderstood by referring to the following detailed description, whichshould be read in conjunction with the accompanying drawings. Thisdescription of one or more particular embodiments, set out below toenable one to build and use various implementations of the technologyset forth by the claims, is not intended to limit the enumerated claims,but to exemplify their application. Without limiting the foregoing, thisdisclosure provides several different examples of techniques formitigating transport path error in a manufacturing apparatus or printer,and/or for fabricating a thin film for one or more products of asubstrate as part of a repeatable print process. The various techniquescan be embodied in various forms, for example, in the form of a printeror manufacturing apparatus, or a component thereof, in the form ofcontrol data (e.g., precomputed correction data or transducer controldata), or in the form of an electronic or other device fabricated as aresult of these techniques (e.g., having one or more layers producedaccording to the described techniques). While specific examples arepresented, the principles described herein may also be applied to othermethods, devices and systems as well.

DETAILED DESCRIPTION

This disclosure provides improved techniques for correcting transportpath error and/or for fabricating a layer on a substrate with a highdegree of positional accuracy. In one embodiment, these techniques areapplied to a manufacturing apparatus or system that produces a layer ofan electronic display, a solar panel or another electronic device orproduct.

More specifically, in specific embodiments discussed herein, a printerdeposits droplets of liquid onto a substrate, where the droplets willmeld to form a continuous coat of liquid, and where the liquid serves asthe source of material will be used to form the desired layer; theliquid for example can be a monomer that is then cured in situ to form apolymer, or it can carry a material that will form the desired layer asthe liquid is dried or baked. During deposition of the droplets, thesubstrate—or another component of the printer such as a camera orprinthead—is advanced along a transport path. The transport path orconveyance system is characterized by very slight imperfections thatcreate at least one error of translational error or rotational erroraffecting deposition of the material and/or individual droplets on thesubstrate. These errors can be repeatable, e.g., in an assembly-linestyle process, imperfections in the transport path can affect every newsubstrate in a predictable way.

To correct for and/or mitigate error, in one embodiment,fine-positioning transducers are driven without a fixed pivot point tocounteract the mechanical imperfections. These transducers perform finetuning of substrate position and/or orientation, and thereby counteractthe effects of the mechanical imperfections in at least one dimension.In this manner, although the conveyance system (e.g., the gripper,substrate, printhead, camera or other transport path) continues to becharacterized by mechanical imperfections, motion of the substrateand/or printhead is made to approximate ideal travel. In one embodiment,a transport path is linear and transport occurs along a first dimension(e.g., the “y”-dimension) while two or more transducers eachindependently apply linear offsets in an independent dimension (forexample, the “x”-dimension). Driven in common mode, these transducerspermit offset of imperfections associated with the conveyance systemwhich affect “x”-dimensional position of the substrate. For example, thetransported thing can be made to travel a virtual straight edge in the“y”-dimension. Driven in differential mode, the transported thing canalso be rotated in the “xy” plane, to correct for orientation error alsocaused by mechanical imperfections of the transport path.

For example, in a split-axis system used for fabricating electronicdevices on a substrate, a “gripper” can be used to move the substratealong a first dimension (e.g., the “y”-dimension). The gripper has afirst component that rides along an edge or track and a second component(typically a vacuum device) that engages and locks to the substrate; thetransducers can be positioned operatively between these components so asto provide selective offset between the first component and the secondcomponent at two or more respective points of interaction, to provideboth common and differential mode displacement as referenced above. Asthe first component experiences translational and rotational excursionscaused by mechanical imperfections in the conveyance system (e.g., in asecond dimension), the transducers are driven so as to exactly equalizethose excursions in that dimension, and essentially provide for thesecond component a “virtual edge” or “virtual transport path”uncharacterized by mechanical error. Note that errors can be linear ornonlinear and the corrections correspondingly can be linear ornonlinear. In optional embodiments, this type of system can be embodiedin a printer or printing system, e.g., with the y-dimension being asubstrate transport dimension and/or one of an “in-scan” or “cross-scan”dimension, and with the x-dimension being a printhead transportdimension and/or the other of the “in-scan” or “cross-scan” dimension.Note that the described techniques even in such a system are not limitedto printhead/substrate transport and, for example, without limitation,can also be applied to correct for motion of a camera, a measurementdevice or other component; note also that the various mentioneddimensions, axes, and associated reference frames are arbitrary and canbe inverted or swapped for other reference frames or for other degreesof freedom.

In one embodiment, mechanical imperfections can be measured in advance,with corrections then stored, computed, “played back” and/or “read out”during each new deposition (e.g., for each ensuing substrate in aseries) so as to counteract repeatable mechanical error in at least onedimension. These corrections can be indexed according to any desiredvariable, for example, transport path position, temperature, specificprint recipe and/or other variables. In such an embodiment, themechanical imperfections can optionally be occasionally or periodicallyremeasured to account for changing conditions (e.g., degradation ofmechanical parts). In an assembly-line style fabrication process forexample, such techniques can be applied to “play” stored errorcorrections as a function of position of the conveyance system (e.g., ofthe first component), to cancel repeatable or predictable motion orposition error.

There may be multiple transport paths in a manufacturing system, andthese techniques can be applied to any one of these transport paths orany combination of them, and can be applied to correct positional errorin one dimension (or rotational error) or errors in multiple dimensions.Several examples will help underscore this point.

First, in one contemplated implementation, these techniques are used tocorrect for cross-scan dimensional error in substrate position as afunction of gripper position along a transport path. A gripper has firstand second components as referenced above and linear transducers thatoperatively couple these components in at least two points ofinteraction, with the transducers structured so as to provide for a“floating” pivot point. As the first component travels down a conveyancepath, the transducers are controlled so as to provide “common-mode” and“differential-mode” offsets that repeatably provide for translationaloffset in the cross-scan dimension and rotational adjustment of thesubstrate. The substrate therefore is advanced in a straight pathnotwithstanding mechanical imperfections of the transport system.Various embodiments of the mentioned transducers will be provided belowbut, briefly, in one embodiment, “voice coils” can be used for thesetransducers, so as to provide very precise, microscopic throws. To helpprovide structural support and interconnection between the first andsecond components, a floating, mechanical pivot assembly compatible withthe common and differential drive modes can also optionally be used.

Second, in an optional extension to this first example, gripper position(and/or the position of the second component of the gripper) can also becorrected in an in-scan dimension. For example, in one embodiment, anelectronic drive signal (used to advance the gripper, or otherwise usedto trigger printer nozzle firing) is adjusted so as to correct forpositional error of the substrate in the in-scan dimension. It is alsopossible to use another transducer (e.g., another voice coil or othertransducer) to offset the first component relative to the secondcomponent in the in-scan dimension. In a first technique, in-scanpositional error can be measured and used to offset individual nozzlefirings (i.e., as the printhead(s) and substrate move relative to eachother, so as to effectuate nozzle firing at precisely the corrected,intended in-scan positions); for example, delays in nozzle firings canbe calculated and programmed into a printhead for each nozzle, withfirings then driven off of a common trigger signal. In a secondtechnique, a common or shared nozzle trigger signal can be generated asa function of gripper position (and/or position of the first componentof the gripper) and can be corrected for error so that the triggersignal is generated so as to simulate error-free movement of thegripper.

In yet another contemplated implementation, the basic techniques can beapplied to correct for error in still other ways. For example, aprinthead assembly that travels in the cross-scan dimension has a firstcomponent that follows a path or edge and a second component that mountsone or more printheads; transducers are used to couple the firstcomponent to the second component in at least two points of interaction,just as referenced above for the gripper, with transducers similarlystructured so as to provide for a “floating” pivot point. As the firstcomponent travels down a conveyance path, the transducers are controlledso as to provide “common-mode” and “differential-mode” offsets thatrepeatably provide for translational and rotational adjustment relativeto the in-scan dimension. Errors in printhead position are thereforemitigated, such droplets are ejected at precisely the correct positionrelative to the printer's frame of reference. Again, various embodimentsof the mentioned transducers will be provided below, but briefly, in oneembodiment, these transducers can also be voice coils which provide formicroscopic throws.

In an optional extension, the first and second components and thetransducers in this second example can be structured so as to insteadprovide for cross-scan dimensional correction, or both in-scan andcross-scan dimensional correction. As alluded to earlier, transducers inthe first example referenced above can also be structured so as toinstead provide for in-scan dimensional correction, or both in-scan andcross-scan dimensional correction (i.e., of substrate position). Thesevarious techniques can be mixed and matched in any desired combinationor permutation. As also alluded to earlier, in one possible application,transducers associated with one conveyance system (e.g., the gripper)can be used to correct for error in another conveyance system (e.g., asa function printhead position along an independent transport path); aswill be further discussed below, such a technique can also be applied tocorrect for discrepancies in coordinate system non-orthogonality.

Reflecting on the principles discussed thus far, at least one transducercan be used to correct for transport path error by displacing a thingbeing transported in a dimension orthogonal to the direction oftransport using both common-mode and differential-mode control. In astill more detailed embodiment, this type of control can be applied tocorrect for transport path error in two different transport paths, forexample, to “y”-axis motion of a first transport system and to “x”-axismotion of a second transport system, using respective sets oftransducers. Correcting two different transport paths in this manner, inone implementation, causing each transported object to follow a virtualstraight edge, facilitates precise correction over deposition and/orfabrication parameters. For example, in the context of a split-axisprinting system, introduced above, correction of both ofgripper/substrate path and printhead path effectively normalizes theprint grid, and provides for a system where the system's understandingof print grid coordinates is precisely correct and is not undermined byerrors in mechanical systems associated with transport. These techniquesand their various combinations and permutations help provide for precisepositional control over deposited droplets, optionally with others ofthe techniques described herein and/or the various documentsincorporated by reference. For example, these techniques can be furtherapplied to “z-axis” (e.g. height) or other dimensional motion control;alternatively, the techniques described herein can be combined withper-nozzle droplet parameters and/or nozzle parameters, as for exampledescribed in U.S. Pat. No. 9,352,561 and US Patent Publication No.20150298153.

This disclosure will roughly be organized as follows: (1) FIGS. 1-2Fwill be used to provide an introduction relating to depositing amaterial on a substrate, causes of fine alignment error and associatedremedies; (2) FIGS. 3A-4D will be used to introduce more specifictechniques, that is, relating to on-line and off-line processes relatingto measuring/detecting and counteracting error in a contemplated printenvironment; (3) FIGS. 5-6E will be used to describe specific mechanicalstructures in one or more detailed embodiments; and (4) FIGS. 7A-B willbe used to discuss a system used to measure and/or prerecord measurementerror for a transport path.

Prior to proceeding to the introduction, it would be helpful to firstintroduce certain terms used herein.

Specifically contemplated implementations can include an apparatuscomprising instructions stored on non-transitory machine-readable media.Such instructional logic can be written or designed in a manner that hascertain structure (architectural features) such that, when theinstructions are ultimately executed, they cause the one or more generalpurpose machines (e.g., a processor, computer or other machine) each tobehave as a special purpose machine, having structure that necessarilyperforms described tasks on input operands in dependence on theinstructions to take specific actions or otherwise produce specificoutputs. “Non-transitory” machine-readable or processor-accessible“media” or “storage” as used herein means any tangible (i.e., physical)storage medium, irrespective of the technology used to store data onthat medium, e.g., including without limitation, random access memory,hard disk memory, optical memory, a floppy disk, a CD, a solid statedrive (SSD), server storage, volatile memory, non-volatile memory, andother tangible mechanisms where instructions may subsequently beretrieved by a machine. The media or storage can be in standalone form(e.g., a program disk or solid state device) or embodied as part of alarger mechanism, for example, a laptop computer, portable device,server, network, printer, or other set of one or more devices. Theinstructions can be implemented in different formats, for example, asmetadata that when called is effective to invoke a certain action, asJava code or scripting, as code written in a specific programminglanguage (e.g., as C++ code), as a processor-specific instruction set,or in some other form; the instructions can also be executed by the sameprocessor or different processors or processor cores, depending onembodiment. Throughout this disclosure, various processes will bedescribed, any of which can generally be implemented as instructionsstored on non-transitory machine-readable media, and any of which can beused to fabricate products. Depending on product design, such productscan be fabricated to be in saleable form, or as a preparatory step forother printing, curing, manufacturing or other processing steps, thatwill ultimately create finished products for sale, distribution,exportation or importation where those products incorporate aspecially-fabricated layer. Also depending on implementation, theinstructions can be executed by a single computer and, in other cases,can be stored and/or executed on a distributed basis, e.g., using one ormore servers, web clients, or application-specific devices. Eachfunction mentioned in reference to the various FIGS. herein can beimplemented as part of a combined program or as a standalone module,either stored together on a single media expression (e.g., single floppydisk) or on multiple, separate storage devices. The same is also truefor error correction information generated according to the processesdescribed herein, i.e., a template representing positional error as afunction of transport path position can be stored on nontransitorymachine-readable media for temporary or permanent use, either on thesame machine or for use on one or more other machines; for example, suchdata can be generated using a first machine, and then stored fortransfer to a printer or manufacturing device, e.g., for download viathe internet (or another network) or for manual transport (e.g., via atransport media such as a DVD or SSD) for use on another machine. A“raster” or “scan path” as used herein refers to a progression of motionof a printhead or camera relative to a substrate, i.e., it need not belinear or continuous in all embodiments. “Hardening,” “solidifying,”“processing” and/or “rendering” of a layer as that term is used hereinrefers to processes applied to deposited ink to convert that ink from afluid form to a permanent structure of the thing being made; these termsare relative terms, e.g., the term “hardened” does not necessarilyrequired that the finished layer be objectively “hard” as long as thefinished form is “harder” than the liquid ink deposited by the printer.The term “permanent,” as in a “permanent layer,” refers to somethingintended for indefinite use (e.g., as contrasted with a manufacturingmask layer which is typically removed as part of the manufacturingprocess). Throughout this disclosure, various processes will bedescribed, any of which can generally be implemented as instructionallogic (e.g., as instructions stored on non-transitory machine-readablemedia or other software logic), as hardware logic, or as a combinationof these things, depending on embodiment or specific design. “Module” asused herein refers to a structure dedicated to a specific function; forexample, a “first module” to perform a first specific function and a“second module” to perform a second specific function, when used in thecontext of instructions (e.g., computer code) refer tomutually-exclusive code sets. When used in the context of mechanical orelectromechanical structures (e.g., an “encryption module,” the term“module” refers to a dedicated set of components which might includehardware and/or software). In all cases, the term “module” is used torefer to a specific structure for performing a function or operationthat would be understood by one of ordinary skill in the art to whichthe subject matter pertains as a conventional structure used in thespecific art (e.g., a software module or hardware module), and not as ageneric placeholder or “means” for “any structure whatsoever” (e.g., “ateam of oxen”) for performing a recited function. “Electronic” when usedto refer to a method of communication can also include audible, opticalor other communication functions, e.g., in one embodiment, electronictransmission can encompass optical transmission of information (e.g.,via an imaged, 20 bar code), which is digitized by a camera or sensorarray, converted to an electronic digital signal, and then exchangedelectronically.

Also, reference is made herein to a detection mechanism and to alignmentmarks or fiducials that are recognized on each substrate or as part of aprinter platen or transport path or as part of a printhead. In manyembodiments, the detection mechanism is an optical detection mechanismthat uses a sensor array (e.g., a camera) to detect recognizable shapesor patterns on a substrate (and/or on a physical structure within theprinter). Other embodiments are not predicated on a sensor array, forexample, a line sensor, can be used to sense fiducials as a substrate isloaded into or advanced within the printer. Note that some embodimentsrely on dedicated patterns (e.g., special alignment marks) while othersrely on recognizable optical features (including geometry of anypreviously deposited layers on a substrate or physical features in aprinter or printhead), each of these being a “fiducial.” In addition tousing visible light, other embodiments can rely on ultraviolet or othernonvisible light, magnetic, radio frequency or other forms of detectionof substrate particulars relative to expected printing position. Alsonote that various embodiments herein will refer to a printhead,printheads or a printhead assembly, but it should be understood that theprinting systems described herein can generally be used with one or moreprintheads; in one contemplated application, for example, an industrialprinter features three printhead assemblies, each assembly having threeseparate printheads with mechanical mounting systems that permitpositional and/or rotational adjustment, such that constituentprintheads (e.g., of a printhead assembly) and/or printhead assembliescan be individually aligned with precision to a desired grid system.Various other terms will be defined below, or used in a manner in amanner apparent from context.

I. INTRODUCTION

FIGS. 1 and 2A-2F are used to introduce several techniques discussed inthis disclosure and some of the problems these techniques address.

More specifically, FIG. 1 represents a prior art process 101 associatedwith some type of transport mechanism. In this specific example, it isassumed that there is a substrate 103 that is to be printed upon withdroplets deposited at selected nodes of a print grid 105; the print grid105 is illustrated as centered in the substrate to denote that in thisposition, it is indented that droplets of ink from the printhead willland at precise positions with predictability that translates to layeruniformity. Note however, that the print grid, while illustrated in thismanner, is defined relative to the printer (not necessarily thesubstrate) and extends to anywhere that printing can occur (e.g., theprintable area can be larger than the substrate). Also, the spacing ofvertical lines and horizontal lines are generally thought to bepredictably spaced, however, this is typically based on an assumptionthat advancement along x and y transport paths are accurate (and/orlinear). Finally, note also that while a printer, substrate and printgrid are exemplified here, these problems are not unique to printers andthat techniques described herein can be applied to a wide variety ofsituations where something is to be mechanically transported, rotated ormoved. The context of a printing process, a substrate and a print gridare to be used as a non-limiting, illustrative example to introduceproblems and techniques described in this disclosure.

It is assumed that printing will occur as the substrate is generallytransported as represented by arrows 104 and, further, that thetransport mechanism is to guide the substrate along a path 107; thispath is illustrated in FIG. 1 as slightly crooked, representing in thisexample mechanical imperfections in the transport mechanism (e.g., insome type of edge guide, track or traveler, or other conveyance systemused to steer the substrate 103). Note that in a typical industrialprinting process, such as for making OLEO display panels as describedearlier, the substrate might be on the order of two meters by threemeters in size, whereas the nonlinearities in path 107 might be on theorder of microns or even smaller. The crookedness (or other error) inpath 107 as depicted in FIG. 1 is thus exaggerated for purposes ofdiscussion and illustration. Whereas error of this scale might beinconsequential in many applications, in certain manufacturing processes(e.g., the manufacture of OLEO displays and/or certain other electronicdevices on large substrates), this type of error might limit achievableproduct size, lifetime, or quality. That is to say, the dropletsgenerally speaking have to be deposited at precise positions so thatthey meld together and produce a homogeneous layer without leaving gapsor pinholes; the droplets upon landing spread only to a limited extent,and surface irregularity in the finished layer can limit achievablelayer thinness and otherwise create quality issues. Even slightmisposition of droplet landing locations can affect product qualityand/or manufacturing reliability.

FIG. 1 as a figure is conceptually divided into two halves, including aleft half and a right half. The left half of the figure shows thesubstrate 103 and a slightly crooked transport path 107. The substrate103 is to be advanced back and forth along this path 107 in what isgenerally designated the “y” dimension, as referenced by arrows 104.Numeral 103 denotes that the substrate is at some point properly alignedwith the print grid 105; the print grid as depicted in this FIG. is anabstraction where vertical lines represent the apparent paths ofrespective nozzles of a printhead as the printhead and substrate aremoved relative to each other, while horizontal lines denote a digitalfiring signal or other ability of a nozzle to be recharged and firerepeated droplets of ink, i.e., the spacings of these horizontal linestypically represent “how fast” the nozzles can be fired. Perhapsotherwise stated, the print grid 105 has nodes, each of which representsan opportunity to eject a droplet of ink; as indicated earlier, it isdesired to deposit ink in a manner that is precisely controlled as toposition, and leaves no pinholes, which is in part achieved as afunction of having precise knowledge as to where each droplet will landon the substrate. Note further that droplets are deposited at discretepositions, but are viscous, and thus typically spread to form acontinuous liquid coat having no gaps or irregularities; volume per unitarea is generally correlated in advance with a desired thickness orother property of the final layer, and thus droplet densities andrelative positions can in theory be selected in a manner (given expecteddroplet size) to produce the desired effect, e.g., to promote an evenlayer of desired thickness following spreading and melding of droplets(this is discussed in U.S. Pat. No. 8,995,022, which is incorporated byreference).

The print grid 105 is graphically depicted at the left-half of the FIG.in a manner “squared up” with the substrate 103, denoting that printingwill general occur at desired droplet landing locations.

Unfortunately, the errors in the transport path 107 (i.e., thecrookedness) can effectively distort the print grid 105, meaning thatdroplets do not necessarily land where they are supposed to relative tothe substrate, because the substrate as advanced experiences finepositional and rotational error. The right hand side of FIG. 1 showssubstrate translation and/or orientation error as the substrate isadvanced from a first position do along the transport path 107, with thesubstrate position and yaw denoted by 103′ relative to a (virtual) ideal“reference edge” 109, to a second position di along the transport path,with the substrate position and yaw denoted by 103″ relative to thereference edge 109. As seen, the substrate experiences, due to theerrors (e.g., crookedness) in the transport path 107, offset androtational error in multiple dimensions; the error in this example isseen to be horizontal and vertical offset Δx₀ and Δy₀, and angularoffset Δθ₀ when the substrate has been moved to the first position d0,and different horizontal and vertical offset Δx₁ and Δy₁, and angularoffset Δθ₁ when the substrate has been advanced to the second transportpath position di. Because the nature of these errors changes as thesubstrate is advanced, these errors distort the print grid, meaning thatalthough a planned print process should (in theory) produce the desiredlayer properties, in fact, droplet deposition can be distorted, creatingpotential quality issues. If left uncorrected, these various errors maycreate pinholes, thin zones and other imperfections and that limit theprecision and/or quality achievable with the printing systems; onceagain, this may limit device size (e.g., it may be difficult toimpossible to produce high quality miniaturized products or productsthat have better quality or resolution, such as very thin large areadisplay screens). The effect of error of the type mentioned is todistort the print grid; for example, while the system and print planningmight effectively assume a rectilinear print grid (105 in FIG. 1),“y”-error and/or jitter (i.e., parallel to the transport path)effectively distorts the separation between the horizontal lines of thatprint grid; similarly, “x”-dimension error and/or jitter effectivelydistorts separation between the vertical lines of that print grid, withthe effect of these errors being that error in the system'sunderstanding of where individual droplets are to be deposited. Thesetypes of errors might result in too little or too great fluid depositionin various pixel wells, or other nonuniformities, potentially leading tobrightness and/or hue variation or other errors in a finished display.

Note also that in this example, the depicted errors in some cases may besimply a repeatable function of the transport path 107, i.e., becausethe transport path in this example is seen as curved, there isnon-linear displacement in the x-dimension, non-linear displacement inthe y-dimension, and nonlinear skew; other types of errors, such asz-dimensional error, pitch and roll, can also potentially occur on arepeatable basis but are not depicted in this particular FIG. Thus, inan application such as an industrial printer used to create fine (e.g.,micron or smaller scale) electronic, optical, or other structures thatrely on uniformity of the type mentioned, and where a series ofsubstrates is to be printed on as part of an “assembly-line” stylefabrication process, the same errors can potentially occur fromsubstrate-to-substrate.

While error in the substrate path has been illustrated, there are alsopotentially other sources of similar error that can affect devicequality and/or process reliability. For example, a split-axis printertypically moves not only the substrate, but a printhead or camera, orother mechanical components. Briefly, in systems that move one or moreprintheads (generally in the “x” dimensions relative to FIG. 1), similarpath error can result in “x,” “y” rotational or other error in theprinthead(s) (relative to the dimensions of FIG. 1). For example, if aprinthead has error at different positions, such typically also has theeffect of distorting the vertical lines of the print grid 105 (i.e.,making them unevenly spaced). Similar analogies can be stated for othertransport path analogies in an industrial printing system of the typereferenced. It is generally desired to reduce the effects of theselayers to improve predictability and reliability in layer fabricationand, generally, to have the ability to fabricate thinner, homogeneouslayers.

FIG. 2A shows one embodiment 201 for reducing or eliminating some ofthese issues. More specifically, FIG. 2A shows the substrate 103 fromFIG. 1 where it is once again assumed that the substrate is to beadvanced back and forth along a path represented by arrows 104. In thisexample, the substrate will be advanced using a gripper 203 that grips acorner or edge of the substrate 103; a first component 204 of thegripper will travel along path 107 (from FIG. 1), generally in the“y”-dimension. The gripper also has two transducers (T), 205 and 206,which operatively connect the first component 204 with a secondcomponent 207, which engages an edge of the substrate. In one exemplarycase, the substrate is supported on an air bearing above a floatationtable which and the substrate's corner is gripped using a vacuummechanism, to provide for nearly frictionless support; in otherexamples, other mechanisms can be used for support and transport. Thetwo transducers each are controlled to displace the second componentrelative to the first component along a common direction (e.g., in an“x” dimension as illustrated in the FIG.), as represented by arrows 210.Each transducer can be independently controlled, leading to a situationwhere “common-mode” control offsets the second component linearly awayfrom the first component 204 in the x-dimension at the respective pointof engagement, while “differential-mode” control pivots second componentrelative to the first about a pivot point “x_(pvt)” Because thetransducers can be electronically driven in a manner having both commonand differential drive components, the pivot point “x_(pvt)” is seen tobe a floating pivot point; in some embodiments, this floating pivotpoint can be an abstract concept, while in others, a mechanicalstructure provides this pivot point while also providing a structuralcoupling between the gripper's two components. The first component 204follows the (error-encumbered path, 107 from FIG. 1), while the secondcomponent locks to the thing being transported (e.g., in this case, thesubstrate 103, e.g., using a vacuum lock). The transducers 205 and 206are seen to be independently controllable to move the substrate asindicated by arrows 208 and 209, and are controlled in a manner so as toexactly negate xdimension- and 8-rotation-induced error in the path 107,with the result that the substrate is moved in a manner that correspondsto an ideal “reference edge” (see line 109 from FIG. 1). Note that inalternative designs, instead of having linear throws that are parallelto one another, transducer 205 could effectuate rotation whiletransducer 206 could effectuate a linear throw, or the transducers couldbe made to produce offsets in the “y” dimension or any other desireddimension, with corresponding effect of mitigating substrate position orrotation error. In FIG. 2A, the gripper's first component 204 movesalong the “y” dimension, while the transducers 205 and 206 each push andpull the substrate along a linear range of motion along the “x”dimension, via contact at respect contact points “c.” Note that eachtransducer in this example can be a linear motor, a piezoelectrictransducer, a voice coil, or another type of transducer.

Note that in the split-axis printing system in this example, thesubstrate is advanced in the “y” dimension relative to the printhead(s)for a particular “scan” or raster motion; the “y” dimension in thisexample therefore also forms the “in-scan” dimension. The printhead(s)are then moved in the “x” dimension to reposition the printhead(s) foran ensuing scan (i.e., in the “cross-scan” dimension); the substrate isthen advanced in the reverse direction, for the ensuing scan, withsuccessive scans continuing until the entire liquid coat has beencreated. The substrate can then be advanced (typically out of theprinter, to another chamber), where it is cured, dried or otherwiseprocessed so as to convert the continuous liquid coat to a permanentstructure having desired electrical, optical and/or mechanicalproperties. The printing system is then ready to receive anothersubstrate, for example, to perform similar printing on that ensuingsubstrate according to a common, predefined “recipe.”

It was noted earlier that error along transport path 107 (from FIG. 1)can lead to error in multiple dimensions, i.e., not just offset in the xdimension. For example, while motion along path 107 might be controlledfor constant velocity, variations in angle of that path might lead tononlinearities in y-position of the substrate as well. For theembodiment of FIG. 2A, this y-dimensional error can optionally becorrected using means 211 for correcting substrate motion in the“in-scan” dimension, for example, using a third transducer 214 toeffectuate throws of the gripper's first and/or second components in thein-scan dimension, to normalize y-dimensional advancement of thesubstrate. In other embodiments, feedback can instead be used to adjustan electronic control signal 215 (e.g., as a feedback signal, deltasignal, or electronic drive signal) for advancement of the gripper, toimpart a slight velocity increase or decrease (Δv) to counteracty-dimensional error, or the gripper's motion can be caused to matchpositional markers (see further below). In yet another optionalembodiment, it is also possible to compute and program individual,y-position dependent nozzle firing delays (as represented by box 217),i.e., the nozzles of the printhead can, in some embodiments, be “told”to print slightly earlier or later as the substrate and printhead(s) aremoved relative to each other in the “y” dimension, in a manner thatexactly cancels out “y” dimension positional error of the substraterelative to the printer. Also, per numeral 219, in another embodiment,it is possible to adjust a “trigger” signal used to time nozzle firing,to have the effect of shifting the horizontal lines of the print grid(see numeral 105 from FIG. 1) so as to cancel out positional error ofthe substrate relative to the printer. Note that “in-scan” or “y-axis”compensation of a gripper is not required for all embodiments.

Reflecting on the subject matter of FIG. 2A, it should be observed thatby using two or more transducers in a mechanical transport system, onecan correct for errors in the transport path or other motion errors(e.g., for a non-linear guide or track or edge). Whereas path errorsmight exist as represented by numeral 107 in FIG. 1, the techniques andstructures introduced above attempt to “live with” this repeatable errorin the transport path (e.g., the gripper's first component 204 continuesto travel this error-encumbered path), but the transducers effectuatethrows or other corrections to negate this path error in at least onedimension, and thus the thing being moved (the substrate in thisexample) travels an idealized path (or at least, is made to simulate anideal edge, such as represented by numeral 109 in FIG. 1). In oneembodiment, these corrections are effectuated by two or moretransducers, each having a linear throw parallel to one another andsubstantially orthogonal to a direction of conveyance (e.g., transducers205 and 206, each independently controllable in a direction (e.g., 210)substantially orthogonal to a direction of arrows 104).

While these techniques can be applied to virtually any mechanicaltransport system, it was earlier mentioned that one field that couldbenefit from these techniques relates to industrial printers where inkdroplets have to be deposited at very precise positions. For example,one contemplated embodiment is as a printer used to fabricate lightemitting devices, such as organic LED display devices (e.g., cell phonescreens, HDTV screens, and other types of displays), and “panel” devicessuch as solar panels. In this regard, in the application discussed above(e.g., where a substrate meters wide and long is printed upon), a numberof conventional systems rely on an air flotation table to advance thesubstrate during printing. The gas ingress and egress in such a systemcan be carefully controlled, to avoid imparting effects to the substrate(e.g., temperature, electrostatic charge buildup or other effects whichmight influence ink behavior) that could potentially produce defects inthe finished layer. In other words, gas flow is used to create a fluidicbearing underneath the substrate, to create a substantially frictionlesssurface that the substrate is moved on during printing; the gripper 203from FIG. 2A in such an application can be a vacuum gripper thatfeatures a single vacuum lock (as part of second component 207) thateffectively engages one contact point on the substrate, or multiplevacuum locks that engage respective contact points along the substrate.In such an application, in order to achieve the “micronscale” (orsmaller) throws used to negate non-linearities and provide for presidepath advancement, the transducers 205 and 206 can advantageously beformed as voice coils which use compression and expansion (i.e., in adirection normal to a direction of force supported by the gas bearing ofthe floatation table) to effectuate the microscopic throws used toachieve precise printhead and nozzle alignment with the substrate. Thatis to say, for electronic flat panel fabrication in particular, and forOLEO display device fabrication in particular, it has been found that(frictionless) flotation support and the use of a vacuum gripper isimportant to minimizing defects and maximizing device lifetime, and theuse of voice coils as the transducers provide an effective component forproviding the required throws in such a system. Other types oftransducers, however, can also be used to achieve throws pertinent tothe particular type of application, for example, through the use ofpiezoelectric transducers, linear motors or other types of transducers.In such a system a floating, mechanical pivot mechanism can be used inaid of the voice coils to provide structural linkage and mechanicalsupport for error correction.

FIG. 2B provides a view 221 similar to the view of FIG. 1, but furtherillustrates ends attainable using the mechanism of FIG. 2A. Morespecifically, FIG. 2B shows the substrate 103 and gripper 203 from FIG.2A as it advances along the path 107. As with FIG. 1, the path 107 isonce again assumed to have error manifested as some form of crookednessor variation; once again, this could be error in an edge guide, track orother mechanism—this error imparts positional and/or rotational error tothe gripper 203. In this case, however, the gripper is seen as havingtransducers “T” which are controlled so as to counteract this error,e.g., in the form of voice coil displacements that compensate for orthat equalize variations in the path 107. Note again that the magnitudeof error is seen as greatly exaggerated relative to the scale of FIG.2B, e.g., in practice, the path may be meters long (e.g., for a 3 meterlong substrate is transported through a room-sized printer), while thecrookedness may be on the order of micron or submicron in scale.

At position d0 of the gripper along the path, it will be recalled fromFIG. 1 that native transport path error was equivalent to Δx0, Δy0, andΔθ0. For the system of FIG. 2B, however, the transducers are actuated todisplace and/or rotate the substrate, as seen at the lower right handside of FIG. 2B and as designated by numeral 103′. That is, thetransducers “T” displace the gripper's second component and thesubstrate relative to the gripper's first component and the track oredge guide 107 so as to have absolute position x3, y3 and θ3. In thecontext of FIG. 2B, the quantity x3 represents an absolute x-positionthat effectively defines a virtual edge 223 offset from theerror-encumbered transport path 107, the quantity y3 corresponds tooptional positioning offset of the substrate to offset it to anarbitrary “smoothed” or normalized advancement relative to the in-scan(or transport) direction, and the quantity θ3 corresponds to a desiredangular orientation of the substrate; for the example of FIG. 2B, it canbe assumed for the moment that y3 and θ3 are “zero,” e.g., that thesubstrate is oriented so as to be exactly vertical (i.e., squared offrelative to the flotation support table, without “y”-dimensionalcorrection, though this need not be the case for all embodiments). InFIG. 2B, the print grid is depicted at numeral 105′ to have a consistentx and θ relationship relative to the substrate 103′; as the substrate isadvanced from position d0 to position dl, the transducers are controlledso as to maintain this consistent positional relationship between thesubstrate and the vertical lines of the print grid, i.e., such that thesubstrate is aligned (notwithstanding error along the path 107) to haveabsolute position x3 and θ3, and is thus depicted at 103″ as havingexactly this relationship relative to the print grid at 105″. Note thatin these examples, although the print grid is illustrated as maintaininga predetermined relationship relative to the substrate, the print gridis defined by the printhead positioning and substrate and printheadconveyance systems, and what is really desired is that the printhead andsubstrate conveyance mechanism maintain a consistent, predeterminedrelationship relative to each other, and that a coordinate systemestablished by this linkage be precisely aligned relative to eachproduct being fabricated; in some embodiments, the substrate (or aproduct being fabricated thereon) is therefore specially alignedrelative to the print grid (i.e., to the printer) via a per-product orper-substrate alignment process—this will be further exemplified below.For the present, it will be assumed that the substrate (e.g., areference edge thereof, or a juxtaposition of fiducials on thesubstrate) is what is being maintained in a predetermined relationshiprelative to the print grid.

Equations are depicted at various positions in the FIG. to indicate howa constant positional relationship is maintained. More specifically, itwill be recalled that native, repeatable error in the transport path 107at position d0 equated to positional and rotational offsets of Δx0, Δy0,and Δθ0. The transducers “T” are therefore controlled so as to addfurther offsets of Δx2, Δy2, and Δθ2, where these values are a functionof position d0 along the transport path and pre-measured error at thecorresponding transport path position (e.g., position d0 along path107). That is, in one embodiment, these values are determined (measured)in advance and are dependent on the negative of the error Δx0, Δy0, andΔθ0, i.e., they exactly cancel the error and optionally offset thesubstrate to some predetermined x/y/θ value. These values can be storedand then used, in combination with a predetermined “recipe” representingfabrication of like-products from many substrates, to print accuratelyon each substrate in a succession or series of substrates in anassembly-line style process. In one embodiment, the depicted transducers“T” only correct the substrate position in x and θ (e.g., any “y”dimensional correction is optionally effectuated using one or more othertransducers or mechanisms not depicted in the FIG.). Note how atposition dl, the transducers are controlled so as to add differentoffset as a function of position on the transport path 107, i.e., to addoffsets of Δx4, Δy4, and Δθ4. As depicted in FIG. 2B, values x5 and θ5can be exactly equal to values x3 and θ3, though once again, this neednot be the case for all embodiments.

It should be noted that in one contemplated embodiment, the printer'ssupport platen (i.e., the flotation table in the example just discussed)has predefined optical markings that provide a position reference systemfor the printer—the print grid is linked to and defined relative to thissystem. The optical markings for example can be formed physically ontothe support table or be added, for example, via an adhesive tape.

Positional control at micron scale or better in many respects is lessintuitive than it might seem, e.g., in one embodiment, each of thegripper transport system and the printhead transport system mounts acamera, which is used to find a common alignment mark and therebyestablish a origin for a coordinate system matching the two transportpaths. This process, and the conveyance systems for each of theprinthead(s) and substrate in such a system, effectively define theprinter's coordinate reference system (and in large part determineconfiguration of a print grid according to which droplets can bedeposited). U.S. Provisional Patent Application No. 62/459,402,incorporated earlier by reference, provides information relating to theuse of these cameras, position detection, and related calibration;basically stated, in addition to finding a common coordinate (or“origin”) point in one disclosed system, each conveyance system uses anoptical tape and optical sensor to provide precise (e.g.,micron-by-micron) position detection and feedback, so the conveyancesystem (e.g., first component of the gripper) “knows” exactly where itis relative to the printer's coordinate system, and these variouscomponents cooperate to effectively define a complete printer coordinatesystem; indeed, the use of such a system can obviate the need fory-dimension gripper path correction, e.g., the gripper is simply drivento the specific position value along the y-dimension.

Once the “origin point” is established by the referencedcamera-alignment process, the two conveyance systems are articulated todetermine relative coordinates between each conveyance system's cameraand a reference point of the conveyance system (e.g., corresponding to aprinthead nozzle position for example), and this then permits a preciseidentification of any point relative to the printer's coordinate system.As noted earlier, in such a system, the printer's “understanding” ofdroplet landing locations is dependent on the print grid, which in turnis defined by this coordinate system; transport path motion error insuch a system could potentially lead to a situation where a particularprint grid location (e.g., associated with an understanding of combinedspecific gripper/printhead position) deviates from actual position ofthese components. By correcting transport path error in the mannersdescribed herein, using the various devices described herein, thispermits the system to correct for that path error such that a substrateand printhead are each positioned in a manner corresponding to printgrid assumptions. In fact, as noted above relative to prerecorded errormeasurement, even errors such as minor non-orthogonality between thetransport paths can be corrected using optional rotational offsets(e.g., non-zero values for θ3 and θ5).

Continuing with the example provided by FIG. 2B, each substrate that isthen introduced into the system has one or more fiducials that areidentified and used to precisely understand position of the substrate(or a panel product thereon) during printing; as each substrate isintroduced, its fiducials are detected (e.g., using one or more of thecameras), and a mechanical system can be used to properly orient/alignthe substrate so as to correspond to an expected position (note thatthis process is not necessary for all embodiments, e.g., it is alsopossible to adjust printer control information to accommodate knownsubstrate misalignment or disorientation).

During a calibration process, a test substrate can be advanced throughthe printer in a manner corresponding to the desired recipe; an opticalinspection device (e.g. a camera) can be used with image processingtechniques to precisely measure positional and rotational error in eachdimension of interest. Motion and/or printing then occurs according tothe desired recipe, and optical inspection is performed continuously orintermittently to measure position and orientation errors as thesubstrate is advanced, e.g., to detect repeatable error that deviatesfrom expected position/orientation as determined relative to advancementof each of the conveyance systems (along their respective paths). Theseerrors and/or corresponding corrections are then stored in digitalmemory of the system (e.g., in an SSD, RAM or other non-transitorymedia) in a manner indexed according to conveyance path position (e.g.,position of the gripper's first component along path 107), according totime, or in another manner. As implied, measured errors are used todevelop repeatable-error correction values for the transducers.

During “live printing” of a substrate in the assembly-line styleprocess, fiducials on each substrate are then once again used todetermine per-substrate precise position relative to the printer and/orrealign/reorient the substrate just as was done with the test substrate.The stored transducer corrections are then retrieved from memory as afunction of gripper/printhead assembly-measured position and used todrive the transducers of the (printhead and/or gripper) error correctionmechanism in order to provide compensating motions that position thesubstrate precisely relative to the printhead. During printing,printhead and gripper positions are continually used with the stored,predetermined error measurements/corrections in order to drive thesubstrate to the correct “cross-scan” position (and/or other position ororientation) of the substrate relative to the flotation table and theprinthead.

The bottom portion of FIG. 2B shows how two linear transducers (e.g.,voice coils) on the gripper can correct for rotational error as well aspositionally offset the substrate in a manner corresponding to anidealized edge (e.g., via displacement in the “x” dimension). Morespecifically, a localized portion of the transport path is designated bynumeral 227 as having a fair amount of curvature, which deviates from anidealized straight edge 109 of the transport path. At two effectivecontact points between the substrate and the transport path (designated“c1” and “c2,” respectively), this error is respectively assumed to be“xi” (depicted as a offset relative to the idealized straight edge in anegative direction) and “xj” (depicted as an offset relative to theidealized straight edge in a positive direction); here, it is assumedthat it is desired to precisely position a left edge of the substrate(or a printable area of the substrate) at absolute position “xk” fromthe idealized transport path (e.g., corresponding to depicted virtualedge 223); numeral 105′ denotes a slight offset of the print grid so asto accommodate the entire range of “x” positional error imparted by thesystem and optionally provide some slight buffer. To effectuate thiscorrection, the positive error at position “c1” (i.e., xi) is furtheroffset by an amount of “xk−|xi|,” while the negative error at position“c2” (i.e., xj) is further offset by an amount of “xk+|xj|.” The twodepicted transducers “T” are controlled to this end and so straightenthe substrate relative to the idealized straight edge; similarcorrections are performed at all other times during movement of thegripper along the transport path 107 in dependent on error at thepertinent position, i.e., such that the substrate follows the virtualpath associated with absolute position “xk.”

Several points should be noted relative to this discussion. First,although the gripper 203 is depicted in this FIG. as a single unit, infact, it can consist of many parts (e.g., the aforementioned first andsecond components, or as a distributed series of 2, 3, 5 or anothernumber of grippers or gripper components that engage the substrate atdifferent locations). Second, while in this embodiment, the twotransducers are depicted as parallel linear actuators (e.g., each avoice coil or piezoelectric transducer), this is not required for allembodiments. That is, depending on embodiment, the transducers “T” canbe coupled in series, and can be rotational, linear or other types ofactuators; in still other embodiments, more than or fewer than twotransducers can be used. Third, it is noted that in various otherembodiments or implementations, the corrections imparted by thetransducers as a function of transport path position can be derivedand/or applied in a number of ways. In a first embodiment, a test device(e.g., a test substrate) having positional sensors (e.g., optical, radiofrequency or other detectors) can be advanced along the transport pathin an offline process and continuously measured for positional and/orrotational error, which is recorded as a function of advancement alongthe transport path. A series of time-based or position-based correctionscan then be developed and formatted as control signals for thetransducers; then, during manufacturing (or other run-time use of thetransport path), an input corresponding to position along the transportpath is received (e.g., a time measurement, a position measurement, ananalog signal or digital signal, or some other value) and is used tolook up or index the proper transducer control signal(s), which is (are)effectively “played back” or otherwise applied as a function oftransport path position (and potentially multiple transport pathpositions). Finally, as noted above, a variety of mechanisms exist toidentify position along the transport path, for example, a signal (e.g.,drive signal, timing signal, etc.) can be used for this purpose, asdenoted by numeral 228, or a position sensor 229 can be used; in onespecifically contemplated embodiment, as referenced above and discussedin U.S. Provisional Patent Application No. 62/459,402, a positionmarking system and position detector is used for each conveyance path,to measure associated position (e.g., for printhead transport andsubstrate transport). Clearly, many alternatives are possible.

As referenced earlier, a fabrication apparatus or system can havemultiple conveyance paths; in the context of a split-axis printer, inone embodiment as referenced earlier, a printer coordinate referencesystem can be defined in dependence on separate printhead and substratetransport paths. FIG. 2C is used to discuss positional error stemmingfrom inaccuracies in a second transport path such as the printheadtransport path. Such a context is generally depicted by numeral 251 inFIG. 2C. A substrate is advanced by a gripper in a first dimension(represented by arrows 104) and a printhead is advanced along a secondtransport path 256 in a second dimension (i.e., represented by arrows254). At a first position 253 of the printhead along the secondtransport path, the printhead experiences error of Δi0, Δj0, and Δφ0;note that the variables i, j and φ represent x and y offsets (andangular rotation in the xy plane), but that i, j and φ are used insteadof x, y and θ to distinguish this example from that of the gripperconveyance system. As denoted in phantom lines at the right side of theFIG., as the printhead is advanced to position 253′, the error becomesΔi1, Δj1, and Δφ1. Once again, this error is a function of positionalong the transport path 256, with change in error potentially beinglinear or non-linear. If left uncorrected, this error would also distortprinting and create the manufacturing precision issues as referencedearlier. Note that in this example, it is assumed that any motion of thesubstrate 103 relative to the gripper's transport path is correctedusing the depicted gripper 203 (and its transducers “T”), but the issueis that the printhead traveler also might create error, resulting in x,y or θ error of the printhead, and which changes the expected landingpositions of droplets ejected from nozzles of the printhead. The effectsof these errors are exemplified relative to an intended print grid 257as indicated by arrow 255, i.e., the effect of unintended printheadrotation (and/or unintended “x”-dimensional displacement) is seen viadistorted print grid 257′ (in analogous fashion, unintended printheadrotation displacement in the “y”-dimension would effectively result in a‘squeezing together’ of vertical print grid lines).

In the context of the FIG., it is also desired that the printheadexperience ideal motion, that is, motion uncharacterized by unintendedmechanical error. That is to say, in this example, it is desired thatthe printhead also follow a virtual, ideal (e.g., straight) transportpath 225, such as will effectively correspond to an unperturbed printgrid (e.g., denoted by numeral 257); this is achieved in one embodimentby causing both virtual, “ideal” gripper motion, denoted by verticalline 109, as well as virtual, “ideal” printhead motion, represented byhorizontal line 225.

In a manner much the same as with gripper path correction, a conveyancesystem for the printhead transport path can optionally also use a set oftransducers to facilitate idealized printhead positioning; to thiseffect, the transducers advantageously provide displacement to anarbitrary “absolute” position that accommodates the entire range of “y”positional error of the printhead optionally provide some slight buffer,such that the printhead motion corresponds to a virtual path 269 thatalso provides a fixed, known position corresponding to the “offset”print grid (105′ from FIG. 2B).

FIG. 2D provides an illustration 261 of a system intended to redressthis type of error. That is, FIG. 2D shows a second transport path 256used to support lateral motion of one or more printheads, in the generaldirection indicated by arrows 254. A printhead assembly includes a firstcomponent 263, which rides along the transport path 256 (e.g., along atrack or guide), and a second component 264, which mounts theprinthead(s). These first and second components are operatively coupledby one or more transducers 265. The transducers in this example are eachlinear actuators which support micro-throws that offset the secondcomponent in the “y” dimension, with common-mode and differential modedrive once again being used to selectively effectuate lineardisplacement and/or xy plane rotation (θ). As denoted by both numeral267 and numeral 267′ (each representing the printhead(s) at respectivepositions along the “cross-scan” or “x” dimension), correction permitsthe printhead(s) to follow a virtual ideal path 269 uncharacterized bymechanical error (i.e., even though the first component 263 continues totravel the error-encumbered second transport path 256). Just as was thecase with the gripper embodiment, the transducers of FIG. 2D can becontrolled to offset the printhead to an absolute y position (i.e.,corresponding to line 269) such that when the printhead is at position267, the aforementioned error of Δi0, Δj0, and Δφ0 is further offset byΔi2, Δj2, and Δφ2, and such that when the printhead is at position 267′,the transducers are controlled to offset the printhead to add offsetΔi4, Δj4, and Δφ4; i and φ typically have a constant value at position267 and position 267′ and are both also typically zero, but again, thisis not required for all embodiments. Just as with the prior gripperexample, the depicted transducer configuration is exemplary only, anddifferent transducers (e.g., rotational transducers) can be used, andcan be applied to different conveyance systems and/or dimensions.Further, just as with the prior example, the depicted transducers inthis embodiment offset the printheads using both common and differentialmode control to effectuate a floating pivot point; the result is that adesired “error free” transport path 225 is offset to an arbitraryposition 269, sufficient to encompass any “y” or in-scan dimensionaljitter which is attributable to imperfections in the second transportpath 256. As indicated by numeral 255′, the result of these corrections(and the optional use of gripper corrections as referenced earlier)effectively normalizes the print grid, as indicated by numeral 257″.Note that as referenced by function box 271, it is also possible to useanother transducer 273 or to use drive signal correction techniques 275to offset position of part or all of the printhead assembly to correctcross-scan positional error.

Reflecting on the principles discussed thus far, correction of each ofthe substrate path to a “virtual,” straight edge, and the printhead pathto a “virtual,” straight edge, permits both of the substrate and theprinthead to be placed in a manner so as to conform to print gridassumptions (e.g., to the printer's coordinate reference system)notwithstanding fine error imparted by the mechanical systems. Thesetechniques may optionally be combined with drive control techniques (orother described techniques to correct each transported thing along itsdimension of transport) to further improve system accuracy. Once again,these techniques can also be extended to other motion dimensions andfabrication and/or mechanical systems as well.

FIG. 2E presents another example 281, namely, an alternative embodimentwhere error in one transport path can be corrected using one or moretransducers “T” associated with a second transport path. In this case,it can be assumed that a gripper assembly 203 includes two lineartransducers that are controlled once again in common- ordifferential-drive modes to effectuate cross-scan and rotationalcorrection without a fixed pivot point. Note that in the case of thisFIG., errors are once again micron or nanometer scale; the depictedangles and offsets are therefore greatly exaggerated in the FIG. toassist with description. In this case, the FIG. shows “two grippers”203, which in reality represent exactly the same gripper and position ofthe gripper along the “in-scan” dimension for two different scans; inthis case, however, one of the conveyance paths (i.e., path 256, for theprinthead assembly) does not have its own error correction system. Thegripper's error correction system is therefore controlled to alsocorrect for printhead conveyance path error, in this case, by linearlysuperimposing offsets to correct for the printhead transport system ontothose corrections used to correct for gripper path error in dependenceon scan. That is to say, in this embodiment, it should be assumed thatthe two grippers represent two alternate sets of transducer controlsignals that respectively correct for printhead system error {Δi0, Δj0,and Δφ0} at printhead position 273′ and {Δi1, Δj1, and Δφ1} at printheadposition 273″ (i.e., corresponding to respective scans). That is, eventhough it was assumed in connection with FIG. 2B that gripper transportin the “y” dimension had been corrected to an ideal edge (relating tothe gripper transport path), through the use of mitigating offsets andangles provided by the gripper systems' transducers, in one embodiment,one may also correct for errors in the printhead path (or anotherindependent transport path) using these same transducers. As depicted,further offset and/or rotations are added so as to effectivelyreposition the substrate so as to have the intended position andorientation relative to the printhead (e.g., to produce motion in a waythat matches printhead error, as denoted by alternate transformed edges107″ and 107″″).

As this discussion implies, while the previous examples show correctionof error in two transport paths, the principles described in referenceto FIG. 2E can be applied to correct for fine error in any number oftransport paths, e.g., one, two, three, four, five and so forth, withcorrections for multiple transport paths being applied to a single drivepath (e.g., to transducers used for substrate conveyance) or to a fewernumber of drive paths. Note that this discussion also applies tonon-orthogonality, e.g., where the gripper and printhead transport pathsare not exactly at ninety degrees separation; this can be treated asequivalent to a case of measured printhead x-position-dependent error.Also, while the term “transport path” is exemplified in the figures aspositional change along a curvilinear path, the principles discussedabove and fine error correction procedures can also be applied tocorrect for fine error in any transport dimension, i.e., includingrotation and accurate angular orientation—for example, in an embodimentwhere a mechanism is rotated, it is possible to measure “jitter” inangular rate of change or orientation, and to use transducers and/ordrive signal correction as exemplified above to correct for such fineerror.

II. MEASURING AND/OR DETECTING AND COUNTERACTING ERROR IN A FABRICATIONAPPARATUS

FIG. 3A is a flow chart that depicts method steps 301 that implementsome of the techniques introduced above. As denoted by numeral 303, themethod can be embodied in a system having a transport path where it isdesired to correct for fine motion, position or orientation error of themotion system; for example, a system can perform high precision product“assembly-line-style” manufacturing using a printer for materialsdeposition, as introduced previously. Error is measured, per 305,optionally in more than one dimension or for more than one transportpath, as indicated by numeral 307. Either this error, or associatedcorrections to be applied to one or more transducers, are then stored indigital memory as a function of path position (or another similarreference, for example, elapsed time, as a function of drive signal,temperature, etc.), per numeral 309. As indicated by numeral 311, in oneembodiment, path position is optically detected using a camera or otheroptical sensor; for example, as referenced earlier, in a split-axisprecision printing system, such a sensor can be used to measure marks onan adhesive tape proximate to the conveyance path, e.g., with alignmentmarks for every micron of travel along the transport path. Duringtransport (e.g., during product manufacture), the stored errors and/orcorrections are read out of memory as a function of this position and/orother factors and used to drive one or more transducers to effectuateposition and/or orientation correction, per numeral 313. As denoted bynumerals 315 and 317, in one embodiment, there can be multipletransducers, each optionally configured so as to effectuate a parallelmicro-throw, optionally without a fixed pivot point, as introduced inFIG. 2A. The result is that the thing being transported follows avirtual, ideal path, as referenced earlier and as identified by numeral319.

FIG. 3B indicates the techniques presented above can be embodied in manydifferent forms to correct transport path error, as denoted generally bynumeral 351. In the context of a printer for manufacturing applications,a print recipe can be stored or cached in advance in a manner that willbe used to repeatably print, e.g., on many substrates on a successivebasis as part of an assembly-line-style process, as indicated by numeral352. As non-limiting examples, the techniques described herein can thenbe applied to correct for repeatable fine motion errors along pathscorresponding to a motion of the substrate, motion of one or moreprintheads or printhead assemblies, motion of a camera assembly orinspection tool, and so forth. Other factors, such as temperature,printhead position, and so forth, can also be used. These techniquespermit automated correction of motion along these transport paths forfine error, such that motion of the substrate (or optionally, any ofthese systems) is made to correspond to an ideal path, notwithstandingthat the actual transport drive mechanism (e.g., motion of a gripper,edge guide, traveler, etc.) is still encumbered by path error whichimparts unintended offsets, non-linearities and other errors. Generallyspeaking, correction is done by a subsystem independent of the printrecipe, in a manner that permits print planning to assume that thesubstrate is ideally placed. For example, the structures describedherein in one embodiment provide means for counteracting an error orunintended offset “Δx” in a first dimension relative to a transportpath, where the first dimension is independent from the transport path(meaning it includes at least one component orthogonal thereto). Suchmeans can comprise at least one transducer that is controlled as afunction of transport path position to reduce or eliminate “Δx,” asdenoted by numeral 353 in FIG. 3B. Such means generally comprisestransducers that are electronically controlled to effectuate positionaldisplacement as a function of position along the transport path, and/orother factors. As represented by numeral 354, these structures (or adifferent, potentially overlapping set of structures) can provide meansfor defining a virtual edge at a specific, arbitrary position in thefirst dimension (e.g., at “x3” in the embodiment from FIG. 2B) andoffsetting a gripper component relative to the transport path (or astructure being transported) to such position; as before, such meansalso generally comprises transducers and associated hardware and/orinstructional logic that causes the transducers to negate or equalizeerror. Per numeral 355, in another embodiment, the structures describedherein provide means for counteracting an error “Δy” in a seconddimension relative to the transport path; this second dimension isoptionally independent from the transport path, but it can also(instead) represent a common dimension to the transport path orotherwise be generally synonymous with the transport path. Such meanscan comprise at least one transducer that is controlled as a function oftransport path position (and/or other factors) to reduce or eliminate“Δy” such as, for example, by correcting position of a transported“thing” for the embodiment depicted above, or for otherwise adjustingvelocity or motion along the transport path. In yet another variation,per numeral 356, the same structures that might be applied to counteract“Δy” can provide means for defining a virtual edge at a specific(absolute or relative) position in the second dimension (e.g., at anon-zero “y3,” relative to the embodiment above) and offsetting thetransport path (or a structure being transported) to such position; suchmeans also generally comprises transducers and logic to cause thetransducers to effectuate positional displacement as a function ofposition along the transport path. In one embodiment, this means canencompass another transport path or associated error correction system,e.g., an error correction system associated with printhead transport(e.g., so as to compensate for nozzle firing times, substrate, printheador other positional error, or other sources of error. In yet anotherembodiment (357), transducers similar to those discussed above can beapplied to counteract rotational error (Δθ); in one embodiment, thismeans can comprise a single transducer that converts electrical energyto structural rotation and, in other embodiments, two or more positionaltransducers can be applied to the same effect. For example, as discussedabove, one implementation can use two voice coils, each a lineartransducer, that when operated independently provide for rotationaladjustment of the thing being transported, with a floating, mechanicalpivot mechanism used to provide structural rigidity in support of thevoice coils. These structures (or a different, potentially overlappingset of structures) can also provide means for defining (358) a virtualedge at a specific (absolute or relative) angular relationship relativeto the first and second dimensions discussed above (e.g., at “θ3” in theembodiment above) and for offsetting the transport path (or a structurebeing transported) in a manner corresponding to such an orientation. Instill another embodiment (359), structures described herein providemeans for counteracting an offset “Δz” in a third dimension relative toa transport path, where the third dimension is optionally independentfrom the transport path, as well as the first and second dimensionsreferenced above. Such means once again can comprise at least onetransducer that is controlled by hardware and/or software logic as afunction of transport path position to reduce or eliminate error;transducers and supporting logic can also be used to define a virtualedge at Z3 (360). Per numeral 361 and an associated set of ellipses,these techniques can be applied to a multitude of dimensions includingcorrection of and/or offset in any of three positional dimensions andany of three rotational dimensions (i.e., yaw, pitch and/or roll). Insome embodiments, as represented by numeral 363, means for correctingfor misalignment can be applied to align a substrate to the printer'sreference system; such means can include position sensor such as acamera, a handler or other transport device, a processor and associatedsupport instructional and/or hardware logic. Per numeral 365, means forcorrecting error in and/or aligning a printhead (PH) can includetransducers with support for a floating pivot point and/or common anddifferential correction modes, as referenced above. Per numeral 366,means for recording error (or correction control for the transducers)can comprise hardware and/or instructional logic and memory. A systemcan also include means (367) for combining error and/or correctionsignals, so as to correct for multiple sources of error (e.g., formultiple transport paths).

It should be noted that each of the referenced dimensional references,e.g., to the “x”, “y”, “θ” or other dimensions is arbitrary, that is,these can refer to any dimension and are not limited to Cartesian orregular or rectilinear coordinates; in one embodiment, the “x” and “y”dimensions respectively correspond to the “cross-scan” and “in-scan”dimensions of a fabrication system, but this need not be the case forall embodiments.

By correcting for motion error in such a manner, the described processesprovide for a “virtual” and/or ideal and/or straight transport path,notwithstanding that a mechanical motion system might still beencumbered, and might continue to track existent, repeatable flaws.Applied in the context of a manufacturing system, such as theaforementioned industrial printers, these techniques provide a powerfultool to enable precision positioning and manufacturing.

FIG. 4A depicts a substrate 401, with a number of dashed-line boxesrepresenting individual panel products. One such product, seen in thebottom left of the FIG., is designated using reference numeral 402. Eachsubstrate (in a series of substrates) in one embodiment has a number ofalignment marks, such as represented by numeral 403. In one embodiment,two such marks 403 are used for the substrate as a whole, enablingmeasurement of substrate positional offset relative to mechanicalcomponents of the printer (e.g., the gripper) and, in anotherembodiment, three or more such marks 403 are used to facilitateadditional adjustments (e.g., rotational adjustment). In yet anotherembodiment, each panel (such as any of the four depicted panels) isaccompanied by per-panel alignment marks, such as marks 405; this latterscheme permits gripper adjustment so that the individual panel beingprinted is precisely aligned to the printer's coordinate referencesystem. Whichever scheme is used, one or more cameras 406 are used toimage the alignment marks in order to identify substrate positionrelative to the printer's coordinate reference system. In onecontemplated embodiment, a single motionless camera is used, and thetransport mechanism of the printer (e.g., a handler and/or air flotationmechanism) moves the substrate to position each alignment mark insequence in the field of view of the single camera; in a differentembodiment, the camera is mounted on a motion system (e.g., a printheadassembly as previously discussed) for transport relative to thesubstrate. The camera can be mounted to a common assembly of theprinthead or a second assembly, to a common traveler used for printheadtransport or to a completely independent traveler, depending onembodiment. In yet other embodiments, low and high magnification imagesare taken, the low magnification image to coarsely position a fiducialfor high resolution magnification, and the high magnification image toidentify precise fiducial position according to a printer coordinatesystem; a line or CCD scanner can also be used. Reflecting on theearlier discussion, in one embodiment, the transport mechanism(s) of theprinter (and associated feedback/position detection mechanisms)control(s) motion to within about a micron of intended position, withthe imaging system used per-substrate to align (and to optionallymechanically reposition) the substrate to the printer's coordinatereference system; prerecorded error or transducer correction signals canthen be applied to correct for repeatable motion error in the mannerdescribed.

In a typical implementation, printing will be performed to deposit agiven material layer on the entire substrate at once (i.e., with asingle print process providing a layer for multiple products). Note thatsuch a deposition can be performed within individual pixel wells (notillustrated in FIG. 4A, i.e., there would typically be millions of suchwells for a television screen) to deposit light generating layers withinsuch wells, or on a “blanket” basis to deposit a barrier or protectivelayer, such as an encapsulation layer. Whichever deposition process isat issue, FIG. 4A shows two illustrative scans 407 and 408 along thelong axis of the substrate; in a split-axis printer, the substrate istypically moved back and forth (e.g., in the direction of the depictedarrows) with the printer advancing the printhead positionally (i.e., inthe vertical direction relative to the drawing page) in between scans.Note that while the scan paths are depicted as linear, this is notrequired in any embodiment. Also, while the scan paths (e.g., 407 and408) are illustrated as adjacent and mutually-exclusive in terms ofcovered area, this also is not required in any embodiment (e.g., theprinthead(s) can be applied on a fractional basis relative to a printswath, as necessary or desired). Finally, also note that any given scanpath typically passes over the entire printable length of the substrateto print a layer for multiple products in a single pass. Each pass usesnozzle firing decisions according to the print recipe, with control overthe transducers (not shown in FIG. 4A) used to ensure that each dropletin each scan is deposited precisely where it should be relative tosubstrate and/or panel boundaries.

FIG. 4B shows one contemplated multi-chambered fabrication apparatus 411that can be used to apply techniques disclosed herein. Generallyspeaking, the depicted apparatus 411 includes several general modules orsubsystems including a transfer module 413, a printing module 415 and aprocessing module 417. Each module maintains a controlled environment,such that printing for example can be performed by the printing module415 in a first controlled atmosphere and other processing, for example,another deposition process such an inorganic encapsulation layerdeposition or a curing process (e.g., for printed materials), can beperformed in a second controlled atmosphere; these atmospheres can bethe same if desired. The apparatus 411 uses one or more mechanicalhandlers to move a substrate between modules without exposing thesubstrate to an uncontrolled atmosphere. Within any given module, it ispossible to use other substrate handling systems and/or specific devicesand control systems adapted to the processing to be performed for thatmodule. Within the printing module 415, as discussed, mechanicalhandling can include use (within a controlled atmosphere) of a flotationtable, gripper, and alignment/fine error correction mechanisms, asdiscussed above.

Various embodiments of the transfer module 413 can include an inputloadlock 419 (i.e., a chamber that provides buffering between differentenvironments while maintaining a controlled atmosphere), a transferchamber 421 (also having a handler for transporting a substrate), and anatmospheric buffer chamber 423. Within the printing module 415, it ispossible to use other substrate handling mechanisms such as a flotationtable for stable support of a substrate during a printing process.Additionally, a xyz-motion system (such as a split-axis or gantry motionsystem) can be used to reposition and/or align the substrate to theprinter, to provide for precise positioning of at least one printheadrelative to the substrate, and to provide a y-axis conveyance system forthe transport of the substrate through the printing module 415. It isalso possible within the printing chamber to use multiple inks forprinting, e.g., using respective printhead assemblies such that, forexample, two different types of deposition processes can be performedwithin the printing module in a controlled atmosphere. The printingmodule 415 can comprise a gas enclosure 425 housing an inkjet printingsystem, with means for introducing a non-reactive atmosphere (e.g.,nitrogen or a noble gas) and otherwise controlling the atmosphere forenvironmental regulation (e.g., temperature and pressure, gasconstituency and particulate presence).

Various embodiments of a processing module 417 can include, for example,a transfer chamber 426; this transfer chamber also has a including ahandler for transporting a substrate. In addition, the processing modulecan also include an output loadlock 427, a nitrogen stack buffer 428,and a curing chamber 429. In some applications, the curing chamber canbe used to cure, bake or dry a monomer film into a uniform polymer film;for example, two specifically contemplated processes include a heatingprocess and a UV radiation cure process.

In one application, the apparatus 411 is adapted for bulk production ofliquid crystal display screens or OLED display screens, for example, thefabrication of an array of (e.g.) eight screens at once on a singlelarge substrate. The apparatus 411 can support an assembly-line styleprocess, such that a series of substrates is processed in succession,with one substrate being printed on and then advance for cure while asecond substrate in the series is concurrently introduced into theprinting module 415. The screens manufactured in one example can be usedfor televisions and as display screens for other forms of electronicdevices. In a second application, the apparatus can be used for bulkproduction of solar panels in much the same manner.

The printing module 415 can advantageously be used in such applicationsto deposit organic light generating layers or encapsulation layers thathelp protect the sensitive elements of OLED display devices. Forexample, the depicted apparatus 411 can be loaded with a substrate andcan be controlled to move the substrate between the various chambers ina manner uninterrupted by exposure to an uncontrolled atmosphere duringthe encapsulation process. The substrate can be loaded via the inputloadlock 419. A handler positioned in the transfer module 413 can movethe substrate from the input loadlock 419 to the printing module 415and, following completion of a printing process, can move the substrateto the processing module 417 for cure. By repeated deposition ofsubsequent layers, each of controlled thickness, aggregate encapsulationcan be built up to suit any desired application. Note once again thatthe techniques described above are not limited to encapsulationprocesses, and also that many different types of tools can be used. Forexample, the configuration of the apparatus 411 can be varied to placethe various modules 413, 415 and 417 in different juxtaposition; also,additional, fewer or different modules can also be used. In oneembodiment, the depicted apparatus 411 can be daisy-chained with othermodules and/or systems, potentially to produce other layers of thedesired product (e.g., via different processes). When a first substratein a series is finished (e.g., has been processed to deposit materialthat will form the layer in-question), another substrate in the seriesof substrates is then introduced and processed in the same manner, e.g.,according to the same recipe.

While FIG. 4B provides one example of a set of linked chambers orfabrication components, clearly many other possibilities exist. Thetechniques introduced above can be used with the device depicted in FIG.4B, or indeed, to control a fabrication process performed by any othertype of deposition equipment.

Once printing is finished, the substrate and wet ink (i.e., depositedliquid) can then be transported for curing or processing of thedeposited liquid into a permanent layer. For example, returning brieflyto the discussion of FIG. 4B, a substrate can have “ink” applied in aprinting module 415, and then be transported to a curing chamber 429,all without breaking the controlled atmosphere (i.e., which isadvantageously used to inhibit moisture, oxygen or particulatecontamination). In a different embodiment, a UV scanner or otherprocessing mechanism can be used in situ, for example, being used onsplit-axis traveler, in much the same manner as the aforementionedprinthead/camera assembly.

FIG. 4C illustrates process flow 431, this time rooted specifically inthe context of a split-axis printer 433. Various process options areillustrated in option blocks 434-437, such as the use of a liquidmonomer as the “ink,” use of a printer enclosure which permits printingto occur in the presence a controlled atmosphere (for the purpose ofminimizing presence of unwanted particulate and/or moisture withdeposited ink), the use of multiple printhead, camera, UV or otherassemblies, and the use of an “assembly-line” style process throughwhich multiple substrates will be sequentially passed and subjected-tothe same manufacturing process(es). Process blocks 439-456 refer to anoffline calibration process that is used to premeasure repeatable errorin the environment of such a printer. For example, for a transport pathfor which error is to be measured, the transported thing is introduced,optionally with appropriate sensors mounted on it to measure positionaland/or rotational error, per numeral 439. This is not required for allimplementations, e.g., in one system, a calibration process advances thegripper and incremental amount and then uses an optical detection system(e.g., predicated on a high resolution camera) to measure the exactposition of substrate fiducials, with interpolation 447 being applied toderive error corresponding to any intermediate positions. In anothercontemplated embodiment, the gripper (e.g., the gripper's “secondcomponent”) mounts an optical device (e.g., a mirror set) which divertsa laser beam, and one or more targets are used to continuously detectmagnitude of “x error” “on the fly” as the gripper is advanced. Clearly,many options will occur to those having ordinary skill in the art.

Whichever error detection system is used, the particular transport pathis then driven according to desired print process 441, with position ofthe thing being transported being measured (e.g., to registeradvancement along the transport path and associate that advancement withfine error with each advancement of a test substrate), 443. As indicatedby option blocks at the right side of the figure, exemplary processesinclude the use of a position signal 444 (e.g., an analog or digitalsignal representing drive of the thing being transported), use of aposition sensor 445, and/or the use of another mechanism 446 to deriveposition. Per numeral 449, for each position along the transport path inquestion, error and/or corrections are computed and used to generate atransducer control signal, which is recorded 451 stored innon-transitory storage 452, in a manner ideally indexed 453 to transportpath position or advancement and/or other factors (or to positions formultiple transport paths, e.g., as a function of current gripperposition and printhead assembly position). Maintaining previousexamples, if a gripper is to be advanced according to a digital positionsignal, then transducer control signals to correct for error can bestored in a manner indexed by digital value of the digital positionsignal associated with the gripper, with a similar value optionallybeing registered as a function of each other transport path positionand/or values of other factors of interest. For embodiments havingmultiple transducers, each independently driven as a function of pathposition, a control signal for each transducer optionally can be storedas a parallel track 454. As further indicated by numeral 455, transducercontrol signals optionally can also be computed in second or additionaliterations for each independent transform mechanism (i.e., such thatcontrol signals are developed for each set of transducers, for example,a set of corrections for the gripper's error mitigation system and a setof corrections for the printhead assembly's error mitigation system). Insituations where one error correction system is to correct for multipletransport paths, then an array of correction signals can be stored as afunction of positions along all associated transport paths. In oneembodiment, as noted earlier, where error mitigation is to be performedby a correction system for one conveyance path to cover error inmultiple conveyance paths, correction signals may be superimposed (orotherwise developed as a function of a mathematical formula or equation)according to each relevant transport path position, for example, error(i,j)=fn{gripperpos(i),printhead assembly:pos(j)}. Other examples willoccur to those having skill in the art. As denoted by numeral 456, wherecorrection is to be a function of multiple transport path positions,correction signal precomputation can include repetition of motion/errormeasurement for each transport path position or for each combination ofrespective transport path positions, optionally treating each transportpath position as an independent degree of freedom.

A dashed line 457 is used to demark offline calibration tasks (above theline) from run-time tasks (below the line).

During run-time, each new production substrate is introduced and aligned459, e.g., to have a normalized relationship in each of x, y and θdimensions. Each transport path (e.g., substrate, printhead, other) isthen driven according to preprogrammed printing instructions, pernumeral 460, i.e., in dependence on the recipe. The position of eachtransport path thing (e.g., substrate, printhead, etc.), per numeral 461(and each other pertinent variable, as appropriate), is then used todirectly index a memory 462 to retrieve error, a position value, atransducer drive value or some other value from which correction and/ordesired position can be identified or computed. Any type of memorysuitable for these purposes and for quick access can be used, forexample, a hard drive, solid state storage, random access memory, flashmemory, a content addressable memory, and so forth, as pertinent to theparticular design. In another embodiment, as mentioned, a formula can bestored and provided to a processor or other circuitry for computation oferror/offset at run-time. Transducer corrections are then output as afunction of conveyance path positions to provide a virtual, perfecttransport path or edge, per numeral 463; as part of this process, if theparticular embodiment is to correct for multiple transport mechanisms ortransport dimensions, each pertinent correction and/or transducercontrol value can at this point optionally be superimposed and/orotherwise combined to produce a correction for aggregate error 465 formultiple transport paths. Per numerals 466 and 467, in one optionaldesign, the system corrects for yaw and translational error (e.g., “x,”“y” and “θ”) in each transport path while in another embodiment, atransport drive signal for one or more of the transport paths can bemodified (e.g., to correct for imperfections that give rise totranslational error in the primary dimension of transport). Transducersare then driven as appropriate 468 in order to equalize mechanicalimperfections in one or more of the transport paths. As noted earlier,in one embodiment, the transducers can include linear transducers, whicheach offset a substrate in a direction normal to gripper path transport,per numeral 469; in another embodiment, offset can produce a “virtualedge” 471 and in yet another embodiment 472, the transducers can be usedto offset an auxiliary path (e.g., a printhead path, gripper drive, andso forth). Printing is performed on the realigned substrate and theprocess ends 473, that is, until the next substrate is introduced. Asshould be apparent, these processes provide a repeatable process thatcan be used to process each substrate in a series.

FIG. 4D provides another flow chart relating to system operation, thistime relating to system alignment, with a series of steps beinggenerally designated using numeral 475. The method begins with systeminitialization, per numeral 476; for example, this initialization can beperformed at each power-up, or on an ad-hoc (e.g., operator-commanded)or periodic basis. An alignment/detection operation 477 is thereafterperformed for the various conveyance paths, for example, to identify anorigin point or common frame of reference, as indicated earlier; asindicated at the left side of the FIG. this operation (or systeminitialization) can be performed if desired following a maintenanceoperation, for example, resulting in a change of the printheads or othersystem components. Note that numeral 478 represents a typical printheadassembly configuration, i.e., where the assembly mounts nine printheads(this may be one large assembly or a number of subassemblies, forexample, three “ink-sticks” that each mount three printheads in astaggered configuration). In one embodiment, there can be 256-1024nozzles per printhead. Optionally, as each printhead is changed, thecalibration then continues per numeral 479 with a gripper system “upwardfacing” camera being used to image the underside of the printhead, tomeasure exact x,y position of each nozzle according to the printer'scoordinate reference system, per numeral 481; that is, each printheadcan feature one or more fiducials which are detected and then used toidentify each nozzle using a search algorithm and image processingtechniques. As necessary, the printhead position can be adjusted (e.g.,inter-printhead spacing adjusted) through the use of stepper motors ormechanical adjustment. Per numeral 483, and as referenced by theprovisional patent application which was earlier incorporated byreference (No. 62/459,402), a camera system mounted by the printheadassembly can similarly be used to identify location of the gripper's“upward-facing” camera, so as to facilitate these various positiondetection functions.

As each substrate is introduced, 485, position of the substrate isprecisely identified and used to align the substrate (and any productsbeing fabricated thereon) to the printer's coordinate reference system.The new substrate is loaded 487, and is roughly aligned with theprinter's transport systems (for example, edge aligned or otherwiseusing an initial transport process). A “downward-facing” camera systemmounted by the printhead assembly is then employed, using a searchalgorithm and suitable image processing, to precisely find one or moresubstrate fiducials, 489; for example, this detection can be performedusing a spiral or similar search pattern which searches about a fiducialexpected position until precise fiducial position and/or orientation hasbeen detected. A series of optional and/or alternative correctionprocesses can then be employed so as to precisely position thesubstrate; for example, as indicated variously by process box 491, inone embodiment, the aforementioned transducers can be driven so as toprovide precise substrate positioning (e.g., a vacuum lock of thegripper's “second component” is not adjusted, but the transducers arearticulated in common- and/or differential-drive modes until thesubstrate fiducial has exactly the right start position and orientation.The transducer positions corresponding to this substrateposition/orientation can then be used as a zero level or position, witherror corrections (during production) then superimposed thereon.Alternatively or in addition, a mechanical handler can be used toreposition the substrate as necessary. As still another alternative, therecipe can be adjusted in software, as disclosed in US PatentPublication No. 20150298153, to correct for alignment error (e.g., withcorrection for repeatable error left for transducers associated with thegripper and/or printhead conveyance systems, as referenced earlier). Pernumeral 493, printing then occurs; following printing, the just-printedsubstrate is unloaded for cure, while the system prepares to receive anew substrate under robotic- or human-direction.

FIG. 5 represents a number of different implementation tiers,collectively designated by reference numeral 501; each one of thesetiers represents a possible discrete implementation of the techniquesintroduced herein. First, techniques as introduced in this disclosurecan take the form of instructions stored on non-transitorymachine-readable media, as represented by graphic 503 (e.g., executableinstructions or software for controlling a computer or a printer).Second, per computer icon 505, these techniques can also optionally beimplemented as part of a computer or network, for example, within acompany that designs or manufactures components for sale or use in otherproducts. Third, as exemplified using a storage media graphic 507, thetechniques introduced earlier can take the form of a stored printercontrol instructions, e.g., as data that, when acted upon, will cause aprinter to fabricate one or more layers of a component dependent on theuse of different ink volumes or positions to mitigate alignment error,per the discussion above. Note that printer instructions can be directlytransmitted to a printer, for example, over a LAN; in this context, thestorage media graphic can represent (without limitation) RAM inside oraccessible to a computer or printer, or a portable media such as a flashdrive. Fourth, as represented by a fabrication device icon 509, thetechniques introduced above can be implemented as part of a fabricationapparatus or machine, or in the form of a printer within such anapparatus or machine. It is noted that the particular depiction of thefabrication device 509 represents one exemplary printer device, forexample, as discussed in connection with the FIG. 4B. The techniquesintroduced above can also be embodied as an assembly of manufacturedcomponents; in FIG. 5 for example, several such components are depictedin the form of an array 511 of semi-finished flat panel devices thatwill be separated and sold for incorporation into end consumer products.The depicted devices may have, for example, one or more light generatinglayers or encapsulation layers or other layers fabricated in dependenceon the methods introduced above. The techniques introduced above canalso be embodied in the form of end-consumer products as referenced,e.g., in the form of display screens for portable digital devices 513(e.g., such as electronic pads or smart phones), as television displayscreens 515 (e.g., OLED TVs), solar panels 517, or other types ofdevices.

Having thus discussed in detail sources of positional error andassociated remedies, this disclosure will now turn to discussion of amore detailed embodiment of a specific fabrication apparatus.

III. SPECIFIC IMPLEMENTATIONS

FIGS. 6A-6E are used to discuss specific printer implementations,namely, as applied to the manufacture of OLED display or solar panels.Depending on product design, the printer seen in these FIGS. can be usedto deposit a layer for an array of products at-once on a substrate(e.g., many smart phone or other portable device displays, perhapshundreds at a time, such as conceptually represented by the individual,arrayed products on substrate 411 from FIG. 4A), or a single product persubstrate such as the display screen of the HDTV 415 or solar panel 417from FIG. 4A. Many other example applications will be apparent to thosehaving skill in the art.

More specifically, FIG. 6A shows a printer 601 as having a number ofcomponents which operate to allow the reliable placement of ink dropsonto specific locations on a substrate. Printing in the illustratedsystem requires relative motion between each printhead assembly and thesubstrate. This can be accomplished with a motion system, typically agantry or split-axis system. Either a printhead assembly can move over astationary substrate (gantry style), or both the printhead assembly andsubstrate can move, in the case of a split-axis configuration. Inanother embodiment, a printhead assembly can be substantially stationarywhile the substrate is moved along both x- and y-axes relative to theprintheads.

The printer comprises a printer support table 603 and a bridge 605; theprinter support table 603 is used to transport substrates (such assubstrate 609) using a planar flotation support surface mounted by aframe 604, while the bridge 605 is used for transport of a number ofprintheads and various support tools, for example, an optical inspectiontool, cure device, and so forth. As noted earlier, a gripper (e.g., avacuum gripper, not seen in this FIG.) provides a “fast axis” forconveying the substrate (e.g., in what is referred to elsewhere hereinas the “y” dimension, see, e.g., dimensional legend 602), while thebridge permits one or more printhead assemblies 611A and 611B to moveback and forth along the bridge 605 along a “slow axis.” To effectuateprinting, a printhead assembly (e.g., the primary assembly 611A) will bepositioned at a suitable position along the bridge while the vacuumgripper moves the substrate in a generally linear manner along the “y”dimension, to provide for a first scan or raster; the printhead assembly611A or 611B is then typically moved to a different position along thebridge 605 and stopped, with the vacuum griper then moving the substrate609 back in the opposite direction underneath the new printhead assemblyposition, and so forth, to provide an ensuing scan or raster, and soforth.

The printer support table 603 can have a porous medium to provide forthe planar floatation support surface. The planar flotation supportsurface includes an input zone, a print zone and an output zone, whichare respectively designated using numerals 606-608; the substrate 609 isdepicted in the input zone 606, ready to be printed on. A combination ofpositive gas pressure and vacuum can be applied through the arrangementof ports or using a distributed porous medium provided by the supporttable. Such a zone having both pressure and vacuum control can beeffectively used to provide a fluidic spring between the flotation tablesurface and each substrate 609. A combination of positive pressure andvacuum control can provide a fluidic spring with bidirectionalstiffness. The gap that exists between the substrate 609 and the surfaceof the flotation table can be referred to as the “fly height,” with thisheight regulated by controlling the positive pressure and vacuum portstates. In this manner, a z-axis height of the substrate can becarefully controlled at various parts of the printer support table,including without limitation, in the print zone 607. In someembodiments, mechanical retaining techniques, such as pins or a frame,can be used to restrict lateral translation of the substrate while thesubstrate is supported by the gas cushion. Such retaining techniques caninclude using spring loaded structures, such as to reduce theinstantaneous forces incident the sides of the substrate while thesubstrate is being retained; this can be beneficial as a high forceimpact between a laterally translating substrate and a retaining meanscould potentially cause substrate chipping or catastrophic breakage. Atother regions of the printer support table, the fly height need not beas precisely controlled, for example, in the input or output zones 606and 608. A “transition zone” between regions can be provided such aswhere a ratio of pressure to vacuum nozzles increases or decreasesgradually. In an illustrative example, there can be an essentiallyuniform height between a pressure-vacuum zone, a transition zone, and apressure only zone, so that within tolerances the three zones can lieessentially in one plane. A fly height of a substrate over pressure-onlyzones elsewhere can be greater than the fly height of a substrate over apressure-vacuum zone, such as in order to allow enough height so that asubstrate will not collide with a printer support table in thepressure-only zones. In an illustrative example, an OLED panel substratecan have a fly height of between about 150 microns (μ) to about 300μabove pressure-only zones, and then between about 30μ to about 50μ abovea pressure-vacuum zone. In an illustrative example, one or more portionsof the printer support table 603 or other fabrication apparatus caninclude an air bearing assembly provided by NewWay Air Bearings (Aston,Pa., United States of America). A porous medium can be obtained such asfrom Nano TEM Co., Ltd. (Niigata, Japan), such as having physicaldimensions specified to occupy an entirety of the substrate 609, orspecified regions of the substrate such as display regions or regionsoutside display regions. Such a porous medium can include a pore sizespecified to provide a desired pressurized gas flow over a specifiedarea, while reducing or eliminating mura or other visible defectformation.

In the example of FIG. 6A, a handler or other conveyance system (notshown) delivers each substrate 609 to the input region 606 of theprinter support table 603. The vacuum gripper engages the substrate 609,transports it from the input zone 606 into the print zone 607 and thenmoves the substrate back-and-forth for printing, to effectuaterespective “near-frictionless,” low-particle-generating, high-speedscans along the fast axis of the printer, according to the particularrecipe. When printing is finished, the vacuum gripper then transportsthe substrate to the output zone 608, where a mechanical handler takesover and conveys the substrate to the next processing apparatus; duringthis time, a new substrate can be received in the input zone 606, andthe vacuum gripper is then transported back to that zone to engage thatnew substrate. In one embodiment, deposited droplets of ink are allowedto meld together in the output zone, e.g., via a brief rest or settlingperiod during which the substrate is allowed to remain in the outputzone, with printing and settling and ensuing cure being performed within a controlled environment (e.g., generally in a nitrogen or noble gasatmosphere, or other non-reactive environment).

The depicted printer 601 also can include one or more maintenance ormanagement bays 612A and 612B, each of which can store tools 615-620 formodular engagement by one or both printhead assemblies, for example,printheads, cameras, “ink sticks;” similarly, in one embodiment, thesebays are configured for interaction with other components, such as adroplet measurement module, a purge basin module, a blotter module, andso forth, optionally within the same enclosed space (enclosure volume)or a second volume. In one embodiment, a printhead assembly cansimultaneously mount three “ink sticks,” as denoted by numeral 622, witheach “ink stick” supporting three printheads and supporting fluidics andcircuit contacts in a manner adapted for modular engagement with theprinthead assembly. The ink delivery system (not separately shown inFIG. 6A) comprises one or more ink reservoirs, ink supply tubing toconvey ink between the reservoirs and one or more of the printheadassemblies, and suitable control circuitry, while the motion system(also not separately shown in FIG. 6A) comprises electronic controlelements, such as a subsystem master processor and control systems andactuating elements for the gripper and printhead assemblies, andsuitable control code.

The printhead assemblies 611A/611B each comprise a traveler 623A/623Bwhich rides along the bridge (i.e., on a track or guide) and anengagement mechanism 624A/624B mounted proximate to a front surface625A/625B of the bridge to robotically engage and disengage each of theink sticks or other tools on a modular basis as desired with eachsupport bay 612A/612B. Each printhead assembly (611A/611B) is supportedby a linear air bearing motion system (which is intrinsicallylow-particle generating) or other linear motion system to allow it tomove along the bridge 605. Each printhead assembly is accompanied byfluidic and electronic connections to at least one printhead, with eachprinthead having hundreds to thousands of nozzles capable of ejectingink at a controlled rate, velocity and size. To provide one illustrativeexample, a printhead assembly can include between about 1 to about 60printhead devices, where each printhead device can have between about 1to 90 printheads, with each printhead having 16 to about 2048 nozzles,each capable of expelling a droplet having of volume of about 1-to-20picoLiters (pL) depending on design. The front surfaces 625A/625B eachprovide for a respective z-axis moving plate which controls height ofthe engagement mechanism (and thus printheads or other tools) above asurface of the substrate. The traveler and engagement mechanism canserve as the “first” and “second” components referenced earlier for theprinthead assembly, e.g., these components in one embodiment are coupledby an electromechanical interface (not seen in FIG. 6A) which permitsrobotic adjustment of the transported tool in each of x, y and zdimensions. In this regard, U.S. Provisional Patent Application No.62/459,402, referenced earlier, provides details relating to z-axiscalibration of printheads and various other elements of the printer'scoordinate reference system in general. The electromechanical interfacecan advantageously include stepper motors, fine adjustment screws andother mechanisms for adjusting (a) x, y and/or z mounting of each toolrelative to the relevant engagement mechanism, and (b) pitch betweenrespective tools (e.g., pitch between ink sticks). In addition, eachtool can also include various fine adjustment mechanisms, e.g., forpitch adjustment between multiple printheads carried by each ink stick.The electromechanical interface can include a kinematic or similar mountfor repeatably and reliably engaging each tool to within a micron ofintended position in each dimension, with robotic adjustment mechanismsoptionally configured to provide feedback for precise positionadjustment of each tool relative to the engagement mechanism.

The electromechanical interface advantageously also includes a set oftransducers as referenced earlier, e.g., to offset the engagementmechanism 624A/624B linearly in the “y” dimension relative to theassociated traveler 623A/623B. As should be apparent from the discussionthus far, provision of a transducer correction mechanism to provide a“virtual straight edge” for the printhead(s) and provision of atransducer correction mechanism to provide another “virtual straightedge” for the gripper (not seen in FIG. 6A) facilitates a print gridwhich is more “regular,” e.g., it helps ensure uniform droplet placementat precise, regular spacings associated with the print grid, therebypromoting enhanced layer uniformity.

As should be apparent, the depicted structural elements permit controlover substrate x-axis position using common mode displacement of thesubstrate by the respective voice coil assemblies, as well as controlover orientation of the substrate about the θ dimension (i.e., rotationabout the z-axis). Various embodiments of the depicted gripper systemcan maintain the orientation of a substrate parallel to the y-axis oftravel to within +/−4300 micro-radians, or less, depending onimplementation. As mentioned earlier, when it is also desired to adjustsubstrate position to further match deviations in printhead (printheadassembly) position and orientation, this control over orientationtogether with common mode x-axis displacement, and the effectiveimplementation of a floating pivot point for the substrate, permitprecision repositioning of the substrate to simulate perfect, virtualedges (or guides) for each of substrate motion and traveler motion(e.g., printhead, camera, etc.). As noted earlier, each of the vacuumgripper and the printhead assembly/traveler also includes an opticalsystem (not seen in the FIG.) for detecting alignment marks, i.e., toprovide an electronic position signal that indicates with precisionlocation of the gripper or printhead assembly along the associatedtransport path.

As should be observed, the use of voice coils in conjunction with air(gas) bearing support of a substrate, as well the vacuum basedengagement between the gripper and substrate, provide an efficientmechanism for a frictionless, effective mechanism for both transportingand fine tuning position of a substrate. This structure helps maintaincontact-minimized interaction with the substrate during electroniccomponent fabrication (e.g., during layer deposition and/or cure), whichhelps avoid distortions and defects which could otherwise be engenderedas a result of substrate deformation, localized substrate temperaturefluctuation induced by contact, or other effects such as electrostaticenergy buildup. At the same time, a near frictionless support andtransducer system, in combination, help provide micron-scale or betterthrows used to perform fine tuning of substrate position. Thesestructures help perform precise substrate corrections necessary toobtain one or more “virtual transport paths,” notwithstanding mechanicalimperfections as referenced earlier, and notwithstanding that asubstrate that serves as the deposition target may be meters long andmeters wide. The voice coils can also be configured to provide arelatively large maximum throw, for example, seven microns or more,which may be important depending on implementation (e.g., when a systemat issue, given its manufacturing tolerances, experiences jitter of thismagnitude).

FIG. 6B shows a vacuum gripper 631 in additional detail. The vacuumgripper 631 once again comprises a first component 633 (which rides atopa y-axis carriage, not seen in the FIG.), a second component 635 whichengages substrates, and two linear transducers 637 and 639. Note that asdepicted, the second component sits vertically above the first componentas both are advanced along the gripper's direction of transport (e.g.,along the “y-dimension” depicted by legend 632); the second componentsupports a vacuum chuck 643 that is used to selectively engagesubstrates. Unlike previous examples predicated on the use of a virtualpivot point, this example further includes a floating mechanical pivotassembly or mechanism 641 which provides a mechanical linkage betweenthe first and second components 633/635 as the gripper is advanced alongthe y-dimension and helps provide structural support for embodimentswhere the linear transducers are embodied as voice coils. The floatingpivot mechanism includes a pivot shaft 651, an assembly upper plate 653(which is mounted to the gripper's second component 635) and an x-axissliding lower plate 655 which moves on rails relative to a support frame644 provided by the gripper's first component 633. The assembly upperplate preferably is made of a relatively thin material to provideflexure, for example, to permit leveling of the gripper's secondcomponent relative to the substrate and the floatation table, and isrigidly affixed to the second gripper's second component using mountingbrackets 656. Succinctly stated, as component 633 is advanced along they-dimension, the floating mechanical pivot mechanism 641 constrains thecomponent 635 to also advance along the y-dimension while permittingx-axis sliding interaction between these components 633/635 and rotationabout a floating pivot axis 649.

The floating pivot point permits differential- or common-mode drive ofthe transducers 637 and 639, as discussed previously; these variousmotions are further represented by sets of motion arrows 645/647.Generally speaking, each transducer couples a mounting block 657 (e.g.,mounted relative to frame 644 of the gripper's first component) and amounting plate 661 (mounted to the gripper's second component), with alinear actuator 659 coupling the mounting block and the mounting plateand providing precise displacement along the x-axis. Numeral 662identifies a linear encoder, which generates a signal for each nanometerof displacement of the associated transducer, i.e., providing feedbackto drive to a precise displacement value. As denoted by dashed-lineoutlines 663 and 665, the design of the transducers 637/639 and floatingmechanical pivot mechanism 641 will be shown and discussed in greaterdetail in connection with FIGS. 6C and 6D.

Notably, FIG. 6B also shows a mechanical banker 658, which provides a“stop” for rough mechanical alignment of each introduced substrate, andan “upward-facing” camera 667, which (again) is used to image a fiducialvia an optical path 669 (represented as a focal cone in the FIG.) forpurposes of aligning the vacuum gripper and printhead assembly (notshown) to define the printer's coordinate reference system, and toidentify relative distance and position of various printhead assemblycomponents (e.g., precise printhead nozzle position and the printheadassembly camera, not shown in the FIG., in terms of the printer'scoordinate reference system).

FIG. 6C shows an enlarged view of the linear transducer 637 from FIG.6B. Once again, the other transducer (designated by numeral 639 in FIG.6B) is generally identical or symmetrical in design to the transducer637.

More particularly, the linear transducer in this example is predicatedon a voice coil design with first and second components 633/635 of thegripper supported on an air bearing. The voice coil is contained withina cylindrical housing 659 to permit displacement of the second component(e.g., the vacuum chuck bar and substrate) relative to the secondcomponent along the general direction of double arrows 645. A adjustmentplate 670 advantageously permits fine adjustments of transducer xyzorientation as between these two components, so as to linearly move thesecond components along the x-dimension axis (see dimensional legend 632in FIG. 6B); once again, this can provided for with a configuration ofmanually adjustable screws that are adjusted and/or calibratedinfrequently. The voice coil once again has a magnet-based design thatprovides for fast, accurate microscopic throws to displace the mountingplate 661 toward and away from the mounting block 657 as a function ofan electronic control signal, i.e., once again, in the direction ofdouble arrows 645.

FIG. 6D shows the floating, mechanical pivot mechanism 641 from FIG. 6B.As noted earlier, an assembly upper plate 653 carries a bushing whichpermits pivot of the assembly upper plate (and the gripper's secondcomponent and vacuum chuck) about a pivot axis 649. This axis is definedby a pivot shaft 651 which extends vertically downward parallel to thez-dimension, and which couples to the x-axis sliding lower plate 655.Although not seen in the FIG., the x-axis sliding lower plate 655 iscoupled to the gripper's first component (via by support frame 644) byrails, so as to permit relatively frictionless x-axis displacement ofthe assembly upper plate 653, the pivot shaft 651, the vacuum chuck 643and the gripper's second component 635 on a general basis relative tocomponent 633 (and support frame 644), all while at the same timeconstraining these two components 633/635 to move together in they-dimension. This structure provides mechanical support for a floatingpivot point, with common-mode and differential-mode voice coildisplacements being used, to respectively provide error-mitigatingoffsets of the second component along the direction of arrows 673 androtation arrows 675. Note that a floating pivot point is not requiredfor all embodiments, e.g., in embodiments where the transducer providessufficient output impedance, a mechanical pivot mechanism can bepotentially omitted. Whether a mechanical support structure is used ornot, a floating pivot point advantageously permits common-mode anddifferential-mode control over multiple transducers, so as to repositiona substrate in x and θ dimensions, and so approximate a “straight edge”ideal transport path; various modifications and alternatives will nodoubt occur to those of ordinary skill in the art.

FIG. 6E provides a schematic view 681, which illustrates elements of thepivot mechanism represented by FIGS. 6B-6D. More specifically, this FIG.now illustrates a linear x-axis rails 683 which effectively provide abearing 685 on either side of the x-axis sliding lower plate 655 topermit that structure (and everything supported above it) to ride intoand out of the drawing page. At the same time, the assembly upper plate653 mounts a bushing 686 so as to permit free rotation of that platerelative to the x-axis siding lower plate 655 about pivot axis 649. Morespecifically, the bushing 686 supports bearings 689 to permit thisrotation. FIG. 6E also illustrates the flexure provided by the assemblyupper plate 653, relative to the gripper's second component 635 andtransducers 637/639.

While the transducer correction mechanisms depicted in FIGS. 6A-6D havebeen exemplified in the context of a gripper assembly, the same basicstructure can also be used for the printhead assembly (or for eachprinthead assembly or other tool carrier). Specifically, a firstcomponent rides a track (or x-axis carriage assembly) atop a gasbearing, while a second component carrying printheads (or other tools)is displaced in a “y” and/or “z” dimension as a function of positionalerror in that dimension as a function of x-axis position (and/or otherfactors, e.g., temperature). For correction in a given dimension, twotransducers are again used with a virtual or floating pivot point toeffectuate both y and θ corrections (or z and xz-plane angularcorrection) in relative position of a printhead relative to a substrate,and in so doing, cause the printhead to follow a virtual straight edgepath. Optionally using two such correction mechanisms together, toprovide straight edge paths for each the gripper and printhead transportsystem, respectively, one may effectively provide for a very precise,regular print grid which provides for greater precision over dropletplacement. Z-axis adjustment of the printhead can also be controlledusing a transducer-based motion correction system of similar design, toprovide for corrections in height of a printhead orifice plate relativeto a substrate surface, and thereby manage height difference to alsohave improved precision. Other degrees of freedom may also be correctedin this manner. In a precision motion system, especially a printer basedfabrication system, where a coordinate reference system used forprinting/manufacture is effectively tied to multiple transport paths,the use of plural correction systems of this type improves precisionover droplet landing location and thus facilitates greater uniformity infabricated layers; in turn, this makes it easier to produce thinnerlayers, e.g., having thicknesses of five microns or less. It again bearsnoting that although the designs discussed above emphasize the use of a“virtual straight edge,” for purposes of improving print gridregularity, all embodiments are not so limited, and nearly any desired“ideal” path can be approximated using the teachings provided here.

IV. ERROR MEASUREMENT

Note that in a system that corrects for repeatable motion error, it isgenerally desired to precisely measure error so as to ensure reliableoperation. This can be performed for the gripper transport system, theprinthead transport system and/or another transport system, asappropriate, using manual as well as automatic error measurementprocesses. A manual process is first described below, followed by a muchless laborious automatic measurement process.

In a first technique, a high-resolution camera can be used to preciselyidentify position and/or orientation of the thing being transported inassociation with advancement along the transport path, optionally ateach advancement point along the transport path, and optionally using asubset of those advancement points and interpolation to identify anerror model for the transport path.

For example, as alluded to previously, in one embodiment, thiscalibration/error measurement can be performed for a gripper conveyancesystem by introducing a test substrate, aligning that substrate to thegripper (e.g., using the high-resolution imaging process as describedearlier, and substrate fiducials), and advancing the substrate accordingto the desired print recipe; however, instead of printing per thecorresponding print recipe, a high resolution camera is transported(incrementally between transport path advancements) in both x and y andused to find the specific position of one or more of the substrate'sfiducials in terms of the printer's coordinate reference system; asearch algorithm and image processing can be used to find preciseposition, which then permits processor derivation of deviation fromexpected coordinates. This error computation (and computation ofmitigating transducer drive signals) can be performed by a calibrationsubsystem (i.e., that is separate from a gripper servo controlsubsystem, with errors/transducer mitigations then being transferred tothe gripper servo control subsystem) or the calibration processes can bedirectly built in to the gripper servo control system. In anotherpossible implementation, it is also possible to print on the entiresubstrate and to then use forensics (e.g., latent image processing) toidentify jitter/corrections dependent on analyzing the printer dropletdeposition pattern; image processing is used to identify droplet landinglocations and/or parameters of a deposited wet or cured film, and toinfer jitter and mitigating corrections from the identifiedlocations/parameters. In yet another possible process, a CCD or linescanner can be used to continuously analyze recognizable features on thesubstrate during deposition and to infer jitter from translational andangular deviations in x and θ as the substrate is dynamically advanced.In much the same manner, a transported printhead can also be analyzed,for example, using an “upward” facing camera to periodically identifyfiducials on a printhead assembly (possibly including individual nozzlepositions), and to identify y and/or z position deviations of theprinthead and changes in the levelness of each printhead orifice plate.For example, it is possible to have a separate camera system image theprinthead(s) at different positions along the dimension of printheadtransport in order to identify minor position and/or angular deviations.

FIG. 7A shows an automatic error measurement process, once again appliedto the gripper conveyance system. It is once again noted that the sameprocess can also be used to measure printhead position (e.g., bymounting interference optics to the printhead assembly as it istransported, and by detecting fine position and angular deviations ofthe printhead assembly along its path of advancement).

FIG. 7A provides an illustrative view, used to depict how substrate (orgripper) positional error is measured. A measurement system is generallyrepresented by numeral 701, and relies on the use of laserinterferometry to measure positional deviation in each of x and ydimensions (in this example), as well as substrate rotation (yaw,denoted elsewhere herein by the variable θ). More specifically, a testsubstrate 703 is held by a vacuum chuck 705 (e.g., carried by thegripper's “second component” as referenced earlier), which hasinterferometry optics 707 mounted to it. The substrate has alignmentmarks, as introduced above, and the gripper also has one or morealignment marks which are located and imaged by a camera or otherimaging system during initial substrate introduction in order toprecisely position the substrate relative to the vacuum chuck; in oneembodiment, a mechanical handler or powered bankers are used toreposition the substrate until proper relative position is achieved,while in a second embodiment, the error compensation system introducedabove (e.g., two or more transducers and floating pivot point) are usedto reposition the substrate to have the proper orientation, with thecorresponding transducer positions being adopted as the “zeroed” orinitialized positions of the error correction system. The substrate andvacuum chuck are then moved along the gripper transport path, asrepresented by numeral 727, ideally just as would be performed as partof the desired print recipe. During this time, a laser 709 emits lightof a specific wavelength, which travels through the gripper-mountedoptics 707 and is directed along one or more paths 727 tomirrors/targets 713, and then bounced back via paths 729 back throughthe optics assembly and to a detector 711. The nature of the targets issuch that if the substrate experiences jitter or deviation along thedimension being measured (e.g., translation or orientation variation),this produces a diffraction pattern that is sensed by the detector 711and used to generate values, which are then fed to a computer 719 andused to compute precise error/position value as a function of positionor advancement of the gripper. Note that the laser interferometry system(laser source 709, detector 711 and targets 713) are mounted in a mannerfixed to a printer chassis 717, whereas it is movement of the optics 707relative to the laser 709 and targets 713 that generates theinterference pattern which is measured for error. Via a suitableconfiguration of the optics, any of x, y, θ, or other dimensional errorcan be measured dynamically as the substrate is advanced; note thatother errors (e.g., z axis or other angular deviations) can also bemeasured depending on how the optics are configured and how manydetectors and/or light sources are used. It is noted that laserinterferometry measurement systems are today used in certain machinetools, and that it is within the level of one or ordinary skill in theart to configure the laser source and/or targets using known techniquesto measure each dimension of interest; for example, a suitableinterferometry system is the “XL-80” laser system available fromRenishaw, PLC, which also publishes training materials on opticspositioning and fine position measurement; it is within the level ofordinary skill to adapt these materials to measurement of substrateand/or gripper position. Following measurement, computation oferror/compensation is then performed by the computer (i.e., by one ormore processors acting under control of suitable software 721); as notedearlier, error and/or corrections 731 can be stored in non-transitorystorage 723 (e.g., a lookup table), for subsequent reading out duringproduction runs in a manner indexed by gripper position and/or otherfactors (e.g., such as temperature, specific recipe, specific panel andso forth).

FIG. 7B is similar to FIG. 7A, but shows a configuration 741 formeasuring fine mechanical imperfections that create error in a printheadposition or camera position in a printing system. As before, a computer719, software 721 and non-transitory storage 723 are used to measureerror. In FIG. 7B, the printhead assembly (or other transported thing)is represented by numeral 745, with interferometry optics mounted tothis assembly as denoted by numeral 743. The assembly moves back andforth as indicated by numeral 755 along a traveler 747, with a lasersource 749, targets 751 and a detector 753 once again being used tomeasure positional deviation in along a dimension being measured. Asbefore, the laser source 749, targets 751 and detector 753 are allprecision mounted to a chassis 717 and do not move during measurement.As FIG. 7B illustrates, any mechanical transport path can be measured inthis manner, and such a path can be independent of a substrate or othertransport path (to which correction transducers are mounted). Onceagain, stored errors and/or correction values 757 can then be read outof non-transitory storage (e.g., a lookup table) as necessary duringfabrication runs, indexed as necessary by printhead/camera positionand/or other factors (e.g., such as temperature, specific recipe,specific panel and so forth).

As referenced earlier, it may be necessary to identify where the cameraand/or printhead is relative to the gripper (not seen in FIG. 7B). Asnoted above, each transport system has one or more alignment marks, andso, the assembly 745 can be moved to a particular location (e.g.,“position zero” at the left side of the traveler 747) concurrent withadvancement of the gripper to its “position zero,” with a search processand camera imaging being used to identify a coordinate system “origin”point as referenced earlier. Similarly a test substrate with alignmentmarks (and known geometry) can then be introduced in order to measureand interrelate coordinate systems pertinent to the gripper (and theflotation table), such that their positional relationship is preciselyknown. This type of processing is also advantageously performed by thecomputer and/or processor 719, acting under the control of suitablesoftware 721.

Automated error measurement processes offer many advantages, includingthat a test run can be performed during a calibration process witherrors and/or corrections being dynamically recorded during thecontinuous operation of each transport system. Recorded errors and/orcorrections can then be played back as described. As necessary, errormeasurement processes can be reperformed, for example, at systemstartup, at milestone events (e.g., printhead change, when apredetermined error threshold is met, or at a periodic interval), or ondemand (or operator command), in order to update or replace previouslyidentified error and/or correction values.

V. CONCLUSION

Reflecting on the various techniques and considerations introducedabove, a manufacturing process can be performed to mass produce productsquickly and at low per-unit cost. Applied to display device or solarpanel manufacture, e.g., flat panel displays, these techniques enablefast, per-panel printing processes, with multiple panels optionallyproduced from a common substrate. By providing for fast, repeatableprinting techniques (e.g., using common inks and printheads frompanel-to-panel), it is believed that printing can be substantiallyimproved, for example, reducing per-layer printing time to a smallfraction of the time that would be required without the techniquesabove, all while guaranteeing precision deposition of ink on aconsistent basis within a desired target area of each substrate. Againreturning to the example of large HD television displays, it is believedthat each color component layer can be accurately and reliably printedfor large substrates (e.g., generation 8.5 substrates, which areapproximately 220 cm×250 cm) in one hundred and eighty seconds or less,or even ninety seconds or less, representing substantial processimprovement. Improving the efficiency and quality of printing paves theway for significant reductions in cost of producing large HD televisiondisplays, and thus lower end-consumer cost. As noted earlier, whiledisplay manufacture (and OLED manufacture in particular) is oneapplication of the techniques introduced herein, these techniques can beapplied to a wide variety of processes, computer, printers, software,manufacturing equipment and end-devices, and are not limited to displaypanels. In particular, it is anticipated that the disclosed techniquescan be applied to any process where a printer is used to deposit a layerof multiple products as part of a common print operation, includingwithout limitation, to many microelectronics applications.

Note that the described techniques provide for a large number ofoptions. In one embodiment, panel (or per-product) misalignment ordistortion can be adjusted for on a product-by-product basis within asingle array or on a single substrate. A printer scan path can beplanned without need for adjustment/adaptation based on one or morealignment errors, such that misorientation of a substrate (or othertransported item, such as a printhead) is automatically compensated forvia transducers which couple a substrate and conveyance system (e.g., agripper). In one embodiment, transducer correction can be used tomitigate error in a different transport path (e.g., a printheadtransport path). Optionally, such corrections can be based onpre-measured error that is expected to repeat from substrate tosubstrate (or panel to panel).

Also, while various embodiments have illustrate the use of a gripper (ormechanism to couple the substrate to a conveyance mechanism), and theuse of two transducers to effectuate fine tuning, other embodiments canuse different numbers of these elements. For example, in one embodiment,two or more grippers can be used, each having their own, dedicatedtransducers. Alternatively, it is possible to use more than twotransducers, and/or transducers for more than two axes of correction. Inaddition, while the techniques described above have been exemplified asapplied to a printer that uses a vacuum gripper system, many otherapplications can benefit from the described techniques includingapplications that use a different type of conveyance mechanism, adifferent type or printer, a different type of deposition mechanism, oranother type of transport path or mechanism. Clearly, many variationsexist without departing from the inventive principles described herein.

The foregoing description and in the accompanying drawings, specificterminology and drawing symbols have been set forth to provide athorough understanding of the disclosed embodiments. In some instances,the terminology and symbols may imply specific details that are notrequired to practice those embodiments. The terms “exemplary” and“embodiment” are used to express an example, not a preference orrequirement.

As indicated, various modifications and changes may be made to theembodiments presented herein without departing from the broader spiritand scope of the disclosure. For example, features or aspects of any ofthe embodiments may be applied, at least where practical, in combinationwith any other of the embodiments or in place of counterpart features oraspects thereof. Thus, for example, not all features are shown in eachand every drawing and, for example, a feature or technique shown inaccordance with the embodiment of one drawing should be assumed to beoptionally employable as an element of, or in combination of, featuresof any other drawing or embodiment, even if not specifically called outin the specification. Accordingly, the specification and drawings are tobe regarded in an illustrative rather than a restrictive sense.

We claim:
 1. An electronic product manufacturing apparatus, comprising:a deposition source to deposit a material on a substrate; a flotationtable to support the substrate on a fluidic cushion while the materialis being deposited thereon; and a substrate transport system,comprising: a first component to travel along a substrate transporttrack according to electronic stimuli, the substrate transport trackextending in a first direction; a second component to selectively engagethe substrate so as to transport the substrate in the first direction;and at least one substrate transport actuator coupling the firstcomponent and the second component, the at least one substrate transportactuator to displace the second component in a second directionorthogonal to the first direction, wherein the at least one substratetransport actuator adjusts position of the second component in thesecond direction as the second component travels along the firstdirection.
 2. The electronic product manufacturing apparatus of claim 1,wherein the deposition source comprises a print head assembly comprisinga print head having nozzles to eject droplets of the material onto thesubstrate, the material including a film-forming material.
 3. Theelectronic product manufacturing apparatus of claim 2, wherein the printhead assembly further comprises a print head assembly transport systemcoupled to a print head assembly track extending in the second direct,wherein the print head assembly transport system further comprises: afirst print head assembly component that travels along the print headassembly track according to electronic stimuli; a second print headassembly component coupled to the print head so as to move the printhead in the second direction; and at least one print head actuatorcoupling the first print head assembly component and the second printhead assembly component, the at least one print head actuator todisplace the second component and the print head in a direction parallelto the first direction; wherein the at least one print head actuatoradjusts position of the second component in the first direction as thesecond component travels along the second direction.
 4. The electronicproduct manufacturing apparatus of claim 2, further comprising asubstrate processing system coupled with the substrate transport systemto form a thin-film layer by solidifying the film-forming material in aprocess of at least one of curing or drying of the film-formingmaterial.
 5. The electronic product manufacturing apparatus of claim 4wherein the thin-film layer further comprises at least one of an organicencapsulation layer of a light-emitting device or an organic lightgenerating layer device of the light-emitting device.
 6. The electronicproduct manufacturing apparatus of claim 1, wherein the second componentcomprises a vacuum chuck to selectively engage the substrate.
 7. Theelectronic product manufacturing apparatus of claim 1 wherein thesubstrate transport system further comprises a mechanical pivot thatcouples the first component and the second component to permit thesecond component to rotate relative to the first component.
 8. Theelectronic product manufacturing apparatus of claim 1, wherein: theelectronic product manufacturing apparatus comprises an enclosure for acontrolled atmosphere; and the deposition source comprises a source ofthe material within the enclosure.
 9. The electronic productmanufacturing apparatus of claim 1, wherein the at least one substratetransport actuator comprises one of a voice coil, a linear motor or apiezoelectric actuator.
 10. An electronic product manufacturingapparatus, comprising: a deposition source to deposit a material on asubstrate; a flotation table to support the substrate on a fluidiccushion while the material is being deposited thereon; and a substratetransport system, comprising: a memory to store predetermined data afirst component to travel along a substrate transport track according toelectronic stimuli, the substrate transport track extending in a firstdirection, a second component to selectively engage the substrate so asto transport the substrate in the first direction, and at least onesubstrate transport actuator coupling the first component and the secondcomponent, the at least one substrate transport actuator to displace thesecond component in a second direction orthogonal to the firstdirection; wherein the at least one substrate transport actuator adjustsposition of the second component in the second direction as the secondcomponent travels along the first direction.
 11. The electronic productmanufacturing apparatus of claim 10, wherein the at least one substratetransport actuator is to be driven according to the predetermined dataand depending on the electronic stimuli.
 12. The electronic productmanufacturing apparatus of claim 10, wherein the at least one substratetransport actuator is to be driven according to the predetermined dataand depending on a position of the first component along the track. 13.The electronic product manufacturing apparatus of claim 10, wherein thefirst component is to be driven according to the predetermined data, andthe predetermined data defines a substrate velocity for the firstcomponent in the first direction.
 14. The electronic productmanufacturing apparatus of claim 10, wherein the deposition sourcecomprises a print head having nozzles to eject droplets of the materialonto the substrate, the material including a film-forming material, andthe print head is to be driven according to a second direction printhead velocity defined by the predetermined data.
 15. An electronicproduct manufacturing apparatus, comprising: a deposition source todeposit a material on a substrate; a flotation table to support thesubstrate on a fluidic cushion while the material is being depositedthereon; and a substrate transport system comprising a first componentto travel along a substrate transport track according to electronicstimuli, the substrate transport track extending in a first direction, asecond component to selectively engage the substrate so as to transportthe substrate in the first direction, and at least two substratetransport actuators coupling the first component and the secondcomponent, the at least two substrate transport actuators to displacethe second component in a second direction orthogonal to the firstdirection; wherein the at least two substrate transport actuators adjustposition of the second component in the second direction as the secondcomponent travels along the first direction so as to cause the secondcomponent to travel along a straight line in the first direction. 16.The electronic product manufacturing apparatus of claim 15, wherein theat least two substrate transport actuators are actuated usingcommon-mode control to displace the second component and the substratein the second direction.
 17. The electronic product manufacturingapparatus of claim 15, wherein the at least two substrate transportactuators are actuated using differential mode control to rotate thesubstrate.
 18. The electronic product manufacturing apparatus of claim15, wherein the substrate transport system further comprises amechanical pivot that couples the first component and the secondcomponent, and wherein the at least two substrate transport actuatorsare actuated using common-mode control to displace the mechanical pivotin the second direction.
 19. The electronic product manufacturingapparatus of claim 18, wherein the mechanical pivot defines a pivotpoint, and the at least two substrate transport actuators are actuatedusing differential mode control to rotate the second component relativeto the first component about the pivot point.
 20. An electronic productmanufacturing apparatus, comprising: a deposition source to deposit amaterial on a substrate; a flotation table to support the substrate on afluidic cushion while the material is being deposited thereon; and asubstrate transport system comprising a first component to travel alonga substrate transport track according to electronic stimuli, thesubstrate transport track extending in a first direction; a secondcomponent to selectively engage the substrate so as to transport thesubstrate in the first direction in a plane of conveyance while thematerial is being deposited thereon; and at least one substratetransport actuator coupling the first component and the secondcomponent, the at least one substrate transport actuator to displace thesecond component in a second direction orthogonal to the first directionand parallel to the plane of conveyance; wherein the at least onesubstrate transport actuator adjusts position of the second component inthe second direction as the second component travels along the firstdirection so as to cause the second component to travel along a straightline in the first direction.
 21. The electronic product manufacturingapparatus of claim 20, wherein the at least one substrate transportactuator is to displace the substrate toward and away from thedeposition source along a third direction orthogonal to the firstdirection and normal to the plane of conveyance.